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Mathematics

Ganita Prakash

All 10 chapters — Patterns, Lines & Angles, Number Play, Data Handling, Primes, Perimeter & Area, Fractions, Constructions, Symmetry and Integers.

10
Chapters
82
FiO Sections
280+
Questions
Chapter 1
Patterns in Mathematics
Discover patterns in numbers, shapes and sequences that form the foundation of mathematics
5FiO Sections
𝒢 Key Concepts
  • Counting numbers: 1, 2, 3, 4, 5, ... (the most basic sequence)
  • Odd numbers: 1, 3, 5, 7, 9, ... (numbers not divisible by 2)
  • Even numbers: 2, 4, 6, 8, 10, ... (numbers divisible by 2)
  • Triangular numbers: 1, 3, 6, 10, 15, 21, ... (dots forming triangles)
  • Square numbers: 1, 4, 9, 16, 25, 36, ... (dots forming squares)
  • Cube numbers: 1, 8, 27, 64, 125, ... (n × n × n)
  • Virahanka (Fibonacci) numbers: 1, 1, 2, 3, 5, 8, 13, ... (each number = sum of previous two)
  • Powers of 2: 1, 2, 4, 8, 16, 32, 64, ... (doubling each time)
  • Shape sequences include regular polygons (triangle, square, pentagon, ...) and Koch snowflake
  • Complete graph K(n) connects every pair of n points; its edges form triangular numbers
📖 Important Terms
SequenceAn ordered list of numbers following a rule
PatternA repeated or predictable arrangement
Triangular numberSum of first n counting numbers: 1+2+3+...+n
Square numberA number that equals n × n for some counting number n
Cube numberA number that equals n × n × n
Complete graphA figure where every point is connected to every other point
Koch SnowflakeA fractal shape made by repeatedly adding triangles to sides
∑ Formulas & Rules
  • Sum of first n odd numbers 1 + 3 + 5 + ... + (2n−1) = n² Example: 1+3+5+7 = 4² = 16
  • n-th Triangular number T(n) = n(n+1)/2 T(4) = 4×5/2 = 10
  • Edges in complete graph K(n) Edges = n(n−1)/2 K(5) has 5×4/2 = 10 edges — same as T(4)!
  • Virahanka/Fibonacci rule F(n) = F(n−1) + F(n−2) Each term is the sum of the two before it
📐 Important Diagrams

Triangular number dots: Row 1 has 1 dot, row 2 has 2 dots, row 3 has 3 dots, etc. Each triangular number is the total dots in the triangle. — T(1)=1, T(2)=3, T(3)=6, T(4)=10

Square number dots: Dots arranged in a square grid. 1×1=1, 2×2=4, 3×3=9, 4×4=16. Notice each square is formed by adding the next odd number as an L-shaped border.

Complete graph K(n): K(2)=1 line, K(3)=triangle (3 lines), K(4)=complete quadrilateral (6 lines), K(5)=pentagram+pentagon (10 lines).

Koch Snowflake: Start with equilateral triangle. On each side, add a smaller equilateral triangle at the middle third. Repeat infinitely for a fractal.

💡 Remember Points

  • Every square number is a sum of consecutive odd numbers starting from 1.
  • Triangular numbers appear as diagonals in the number grid and as edges of complete graphs.
  • Virahanka numbers were discovered in India centuries before Fibonacci!
  • Adding two consecutive triangular numbers gives a square number: T(n)+T(n−1) = n².

⚠ Common Mistakes

  • Confusing square numbers (1, 4, 9, 16) with even numbers (2, 4, 6, 8) — they are different sequences.
  • Forgetting that the Virahanka/Fibonacci sequence starts 1, 1, 2, 3, 5... (two 1s at the start).
  • Mixing up triangular and square numbers — T(4)=10, but 4²=16.

✏ Figure it Out Sections
  • 1

    What is Mathematics?

    Everyday examples of mathematics — temples, structures, daily life applications.

    2 Qs
  • 2

    Patterns in Numbers

    Recognising and extending number sequences, completing pattern tables.

    2 Qs
  • 3

    Visualising Number Sequences

    Shape sequences — drawing the next shape and describing the formation rule.

    2 Qs
  • 4

    Relations among Number Sequences

    Regular polygons, complete graphs — connecting shapes to number sequences.

    2 Qs
  • 5

    Number and Shape Sequences

    Stacked squares, stacked triangles, Koch Snowflake — advanced pattern exploration.

    5 Qs
Chapter 2
Lines and Angles
Points, rays, segments, angle types, measurement and construction
11FiO Sections
𝒢 Key Concepts
  • A point marks an exact location; it has no size.
  • A line segment has two endpoints and a fixed length.
  • A ray starts at one point and extends infinitely in one direction.
  • A line extends infinitely in both directions.
  • An angle is formed when two rays share a common starting point (vertex).
  • Angles are measured in degrees (°) using a protractor.
  • A full rotation = 360°; a straight angle = 180°; a right angle = 90°.
  • Angles in real life: clock hands, opening of doors, slopes of ramps.
  • At h o'clock, the angle between hands = 30 × h degrees.
  • Always place the protractor's centre on the vertex and one ray on the baseline.
📖 Important Terms
PointA location in space, represented by a dot
Line segmentPart of a line with two fixed endpoints
RayPart of a line with one endpoint, extending infinitely
VertexThe common point where two rays meet to form an angle
Acute angleAn angle less than 90°
Right angleAn angle exactly equal to 90°
Obtuse angleAn angle between 90° and 180°
Straight angleAn angle exactly equal to 180°
Reflex angleAn angle between 180° and 360°
ProtractorA tool used to measure and draw angles
∑ Formulas & Rules
  • Full rotation 1 full turn = 360°
  • Right angle 1 right angle = 90° = ¼ turn
  • Straight angle 1 straight angle = 180° = ½ turn
  • Clock angle formula Angle at h o'clock = 30 × h degrees At 3 o'clock: 30×3 = 90° (right angle)
📐 Important Diagrams

Angle types visual: Acute angle — arms close together (like a narrow V). Right angle — arms form an L with a small square at vertex. Obtuse angle — arms spread wider than L. Straight angle — arms form a flat line.

Protractor placement: Centre point on vertex, baseline aligned with one ray. Read the scale where the other ray crosses — use the inner or outer scale depending on which starts at 0°.

Clock angles: 12 o'clock = 0°, 3 o'clock = 90°, 6 o'clock = 180°, 9 o'clock = 270°.

💡 Remember Points

  • Right angle has a small square symbol at the corner — look for it in diagrams.
  • Acute = "a-cute" little angle (small); Obtuse = "obese" large angle (big).
  • Each hour on a clock = 30° (since 360° / 12 hours = 30°).
  • A straight angle looks like a straight line — the two rays point in opposite directions.

⚠ Common Mistakes

  • Reading the wrong scale on a protractor (inner vs. outer). Always check which scale starts at 0° on your baseline ray.
  • Confusing a ray (one endpoint, infinite) with a line segment (two endpoints, finite).
  • Forgetting that reflex angles (>180°) exist — not every angle is less than 180°.

✏ Figure it Out Sections
  • 1

    Points, Lines, Rays and Segments

    Identifying and drawing basic geometric elements.

    6 Qs
  • 2

    Angles

    Understanding what angles are and how they are formed.

    6 Qs
  • 3

    Comparing Angles

    Using superimposition and other methods to compare angles.

    3 Qs
  • 4

    Right Angles

    Identifying right angles in the environment and shapes.

    4 Qs
  • 5

    Types of Angles

    Acute, obtuse, right, straight and reflex angles.

    4 Qs
  • 6

    Measuring Angles (Unmarked Protractor)

    Estimating angles without marked scales.

    1 Q
  • 7

    Measuring with Protractor

    Using a protractor to measure angles accurately.

    2 Qs
  • 8

    More Angle Measurement

    Practice measuring various angles and finding unknown angles.

    7 Qs
  • 9

    Errors in Measurement

    Common mistakes when using a protractor and how to avoid them.

    1 Q
  • 10

    Angles Around Us

    Real-world angle applications — clocks, doors, slopes.

    5 Qs
  • 11

    Drawing Angles

    Constructing angles of given measures using a protractor.

    3 Qs
Chapter 3
Number Play
Supercells, digit sums, palindromes, estimation and number games
8FiO Sections
𝒢 Key Concepts
  • Supercell: A number in a grid that is greater than all its neighbours (up, down, left, right).
  • Digit sum: Add all digits of a number repeatedly until you get a single digit (e.g., 587 → 5+8+7=20 → 2+0=2).
  • Palindrome: A number that reads the same forwards and backwards (e.g., 121, 1331, 45654).
  • Kaprekar’s routine: For any 4-digit number (not all digits same), arrange digits descending − ascending. Repeat. Always reaches 6174.
  • Collatz conjecture: Start with any number. If even, halve it; if odd, triple it and add 1. You always reach 1 (unproven but works for all tested numbers).
  • Estimation: Rounding numbers to the nearest 10, 100 or 1000 before calculating for quick approximate answers.
  • There are 9 one-digit numbers (1–9), 90 two-digit numbers (10–99), and 900 three-digit numbers (100–999).
  • Every number can be reversed to check for palindrome patterns.
📖 Important Terms
SupercellA cell whose value exceeds all its adjacent cells in a grid
Digit sumSum of all digits of a number, repeated until single digit
PalindromeA number (or word) that reads the same in both directions
Kaprekar constant6174 — the fixed point of the Kaprekar routine for 4-digit numbers
EstimationFinding an approximate value by rounding
RoundingReplacing a number with the nearest ten, hundred, etc.
∑ Formulas & Rules
  • Count of n-digit numbers 1-digit: 9 | 2-digit: 90 | 3-digit: 900 | n-digit: 9 × 10^(n−1)
  • Kaprekar routine (4-digit) Descending order − Ascending order → repeat → reaches 6174 Example: 3087 → 8730−0378 = 8352 → 8532−2358 = 6174
  • Collatz rule Even: n/2 | Odd: 3n+1 12 → 6 → 3 → 10 → 5 → 16 → 8 → 4 → 2 → 1
📐 Important Diagrams

Supercell grid: A rectangular grid of numbers where you circle cells that are larger than all their neighbours. Corner cells have 2 neighbours, edge cells have 3, interior cells have 4.

Number line jumps: Showing skip counting (by 2s, 3s, 5s) as arcs on a number line — landing spots reveal multiples and patterns.

💡 Remember Points

  • 6174 is the Kaprekar constant — any 4-digit number (with at least two different digits) reaches it.
  • All single-digit numbers are palindromes.
  • Digit sum of any multiple of 9 is always 9.
  • When estimating, round to the nearest convenient place value for the problem.

⚠ Common Mistakes

  • In supercells, forgetting to check diagonal neighbours are NOT counted — only up/down/left/right.
  • Applying Kaprekar’s routine to numbers with all identical digits (like 1111) — it doesn’t work for those.
  • Confusing digit sum with just adding digits once — you must repeat until single digit.

✏ Figure it Out Sections
  • 1

    Supercells Introduction

    What are supercells and how to identify them in number grids.

    7 Qs
  • 2

    Supercells

    More practice with supercells — finding largest neighbours.

    10 Qs
  • 3

    Number Line Patterns

    Patterns on number lines, jumps and skip counting.

    6 Qs
  • 4

    Digit Sums

    Finding digit sums and exploring their properties.

    3 Qs
  • 5

    Clock, Calendar, and Kaprekar

    Number play with clock arithmetic, calendar patterns and Kaprekar’s routine.

    5 Qs
  • 6

    Mental Math

    Quick mental calculation strategies.

    2 Qs
  • 7

    Estimation

    Rounding, estimating sums, differences and products.

    6 Qs
  • 8

    Games and Strategies

    Number games — winning strategies and logical reasoning.

    10 Qs
Chapter 4
Data Handling and Presentation
Collecting, organising and representing data using tally marks, pictographs and bar graphs
7FiO Sections
𝒢 Key Concepts
  • Data: Information collected through surveys, observations or experiments.
  • Tally marks: A quick way to count — four vertical lines with a diagonal fifth line crossing them (groups of 5).
  • Frequency: The number of times a particular value appears in data.
  • Frequency table: A table showing each category and its frequency (count).
  • Pictograph: Uses pictures or symbols to represent data. Each symbol stands for a certain number (the key/scale).
  • Bar graph: Uses bars of equal width to represent data. Height of bar = frequency.
  • In bar graphs, bars must have equal gaps between them and be drawn on a uniform scale.
  • The title and labels on axes are essential parts of any graph.
📖 Important Terms
DataRaw facts and figures collected for analysis
Tally marksLines used for counting, grouped in fives: ∣∣∣∣ crossed = 5
FrequencyHow many times a value occurs in data
PictographA graph using pictures/symbols to show data
Key / ScaleTells what each symbol represents in a pictograph
Bar graphA graph using rectangular bars to compare quantities
TitleThe heading that describes what the graph shows
∑ Formulas & Rules
  • Tally count ∣∣∣∣ with diagonal = 5 Always group in sets of 5 for easy counting
  • Pictograph reading Total = Number of symbols × Key value If key says 1 symbol = 10 students, 3 symbols = 30 students
  • Bar graph rule All bars same width, equal gaps, uniform scale on y-axis
📐 Important Diagrams

Tally marks example: Counting favourite fruits — Apple: ∣∣∣∣ ∣∣ (7), Banana: ∣∣∣∣ (5), Mango: ∣∣∣ (3). Transfer to a frequency table.

Bar graph structure: X-axis shows categories (horizontal), Y-axis shows frequency with a uniform scale. Each bar is the same width. Title on top. Scale marked at equal intervals.

💡 Remember Points

  • Always include the key in a pictograph — without it, the graph is meaningless.
  • Choose a convenient scale for bar graphs so that the tallest bar fits the page.
  • The sum of all frequencies should equal the total number of data points collected.
  • Half-symbols in pictographs represent half the key value.

⚠ Common Mistakes

  • Drawing bars of unequal widths in a bar graph — all bars must be the same width.
  • Forgetting to write the title or label the axes on a graph.
  • Miscounting tally marks — always cross-check by adding the frequency column.

✏ Figure it Out Sections
  • 1

    Collecting Data

    Methods of data collection — surveys, observations.

    4 Qs
  • 2

    Tally Marks

    Recording data using tally marks and frequency tables.

    2 Qs
  • 3

    Frequency

    Understanding and computing frequency from raw data.

    3 Qs
  • 4

    Collecting Data Continued

    Extended data collection exercises and organisation.

    2 Qs
  • 5

    Pictographs

    Reading and drawing pictographs to represent data.

    2 Qs
  • 6

    Bar Graphs Reading

    Interpreting bar graphs — extracting and comparing data.

    4 Qs
  • 7

    Drawing Bar Graphs

    Constructing bar graphs from given data sets.

    2 Qs
Chapter 5
Prime Time
Factors, multiples, prime numbers, prime factorisation and divisibility rules
6FiO Sections
𝒢 Key Concepts
  • A factor of a number divides it exactly (no remainder). Example: factors of 12 are 1, 2, 3, 4, 6, 12.
  • A multiple of a number is obtained by multiplying it by 1, 2, 3, ... Example: multiples of 5 are 5, 10, 15, ...
  • A prime number has exactly 2 factors: 1 and itself. Examples: 2, 3, 5, 7, 11, 13, ...
  • A composite number has more than 2 factors. Examples: 4, 6, 8, 9, 10, ...
  • 1 is neither prime nor composite — it has only one factor.
  • 2 is the only even prime number.
  • Sieve of Eratosthenes: A method to find all primes up to a given number by crossing out multiples.
  • Prime factorisation: Writing a number as a product of prime factors using a factor tree.
  • Co-prime numbers: Two numbers whose only common factor is 1. Example: 8 and 15 are co-prime.
  • Twin primes: Pairs of primes that differ by 2 (e.g., 3&5, 5&7, 11&13, 17&19).
📖 Important Terms
FactorA number that divides another number exactly
MultipleThe product of a number with any counting number
Prime numberA number with exactly two factors (1 and itself)
Composite numberA number with more than two factors
HCFHighest Common Factor — the largest factor shared by two numbers
LCMLowest Common Multiple — the smallest multiple shared by two numbers
Co-primeTwo numbers with HCF = 1
Perfect numberA number equal to the sum of its factors (excluding itself). E.g., 6 = 1+2+3
Twin primesA pair of primes differing by 2
∑ Formulas & Rules
  • Divisibility by 2 Last digit is 0, 2, 4, 6, or 8 (even)
  • Divisibility by 3 Sum of digits is divisible by 3 Example: 372 → 3+7+2 = 12 → 12÷3 = 4 ✓
  • Divisibility by 4 Last two digits form a number divisible by 4 Example: 1324 → last two digits 24 → 24÷4 = 6 ✓
  • Divisibility by 5 Last digit is 0 or 5
  • Divisibility by 9 Sum of digits is divisible by 9
  • Divisibility by 10 Last digit is 0
  • Perfect numbers 6 = 1+2+3   |   28 = 1+2+4+7+14
📐 Important Diagrams

Sieve of Eratosthenes: Write numbers 1 to 100 in a grid. Cross out 1. Circle 2 and cross out all its multiples. Circle 3 and cross out all its multiples. Continue with 5, 7. All remaining uncrossed numbers are prime.

Factor tree: Break a number into two factors, then keep breaking until all leaves are prime. E.g., 60 → 6 × 10 → (2×3) × (2×5) → 60 = 2² × 3 × 5.

💡 Remember Points

  • 1 is NOT prime and NOT composite. It is a special number.
  • The smallest prime is 2, and it is the only even prime.
  • Every even number greater than 2 is composite (divisible by 2).
  • To check if a number n is prime, test divisibility only up to the square root of n.
  • Co-prime numbers need not themselves be prime (e.g., 4 and 9 are co-prime).

⚠ Common Mistakes

  • Calling 1 a prime number — it is neither prime nor composite.
  • Confusing factors (finite, divide the number) with multiples (infinite, are divided by the number).
  • Forgetting to check all prime factors in the Sieve — stopping after crossing out multiples of 2 and 3 misses composites like 49 (7×7).

✏ Figure it Out Sections
  • 1

    Common Multiples — Idli-Vada Game

    Finding common multiples through a fun game context.

    4 Qs
  • 2

    Factors — Jump Game

    Understanding factors using number-line jumps.

    10 Qs
  • 3

    Prime Numbers

    Identifying primes, Sieve of Eratosthenes, properties of primes.

    12 Qs
  • 4

    Prime Factorisation

    Breaking numbers into prime factors using factor trees.

    5 Qs
  • 5

    Co-primality

    Pairs of numbers with no common factor other than 1.

    4 Qs
  • 6

    Divisibility Tests

    Rules for divisibility by 2, 3, 4, 5, 6, 9, 10.

    7 Qs
Chapter 6
Perimeter and Area
Measuring boundaries and surfaces of shapes, grid paper techniques and tangram relationships
11FiO Sections
𝒢 Key Concepts
  • Perimeter is the total length of the boundary of a closed shape.
  • Area is the amount of surface enclosed within a shape.
  • Perimeter is measured in length units (cm, m); area in square units (cm², m²).
  • On grid paper: count full squares as 1, more-than-half as 1, less-than-half as 0, exactly half as ½.
  • Tangram pieces can rearrange to form different shapes — total area stays the same.
  • Two shapes can have the same area but different perimeters and vice versa.
  • Splitting a shape and rearranging changes the perimeter but not the area.
  • A triangle formed by cutting a rectangle diagonally has half the rectangle’s area.
📖 Important Terms
PerimeterTotal distance around a closed shape
AreaAmount of surface a shape covers, in square units
Unit squareA square with side 1 unit — used to measure area
TangramA Chinese puzzle of 7 pieces that form a square
Grid paperPaper with squares used for measuring area
∑ Formulas & Rules
  • Perimeter of rectangle P = 2 × (length + breadth) = 2(l + b)
  • Perimeter of square P = 4 × side = 4s
  • Perimeter of equilateral triangle P = 3 × side = 3s
  • Area of rectangle A = length × breadth = l × b
  • Area of square A = side × side = s²
  • Area on grid paper Full square = 1 | > half = 1 | < half = 0 | exactly half = ½
  • Triangle (half of rectangle) Area of triangle = ½ × base × height
📐 Important Diagrams

Rectangle with labels: Length (l) on the longer side, breadth (b) on the shorter side. Perimeter goes all around: l + b + l + b = 2(l+b). Area fills the inside: l × b square units.

Grid paper area counting: An irregular shape on squared paper. Count full squares inside, estimate partial squares using the half rule. Add up for total area.

Same area, different perimeter: A 1×12 rectangle and a 3×4 rectangle both have area 12 sq units, but perimeters are 26 and 14 units respectively.

💡 Remember Points

  • Same area does NOT mean same perimeter — always check both.
  • Among all rectangles with the same perimeter, the square has the largest area.
  • Perimeter is a 1D measurement (cm, m); area is a 2D measurement (cm², m²).
  • When rearranging pieces, area is preserved but perimeter may change.

⚠ Common Mistakes

  • Writing area in cm instead of cm² — area must always have square units.
  • Forgetting to multiply by 2 in the perimeter formula: P = 2(l+b), not just l+b.
  • On grid paper, counting a less-than-half square as 1 — it should be counted as 0.

✏ Figure it Out Sections
  • 1

    Perimeter Basics

    Understanding perimeter as the total boundary length.

    6 Qs
  • 2

    Running Track

    Perimeter problems using a running track context.

    3 Qs
  • 3

    Perimeter on Dot Grid

    Finding perimeter of shapes drawn on dot grids.

    3 Qs
  • 4

    Split and Rejoin

    How splitting and rejoining shapes changes perimeter.

    3 Qs
  • 5

    Area

    Introduction to area as the surface covered by a shape.

    4 Qs
  • 6

    Tangram

    Exploring area relationships using tangram pieces.

    8 Qs
  • 7

    Area on Squared Paper

    Counting squares to find area of irregular shapes.

    6 Qs
  • 8

    Explore Rectangles with Area 24

    Finding all rectangles with a given area.

    3 Qs
  • 9

    Area of Triangles

    Relating triangle area to rectangle area.

    5 Qs
  • 10

    Using 9 Unit Squares

    Arranging unit squares to form different shapes and areas.

    4 Qs
  • 11

    House Plan

    Calculating perimeter and area from a house floor plan.

    2 Qs
Chapter 7
Fractions
Equivalent fractions, comparing, simplifying, adding and subtracting using Brahmagupta’s method
6FiO Sections
𝒢 Key Concepts
  • A fraction represents a part of a whole: numerator (top) / denominator (bottom).
  • Unit fraction: A fraction with numerator 1, e.g., ½, ⅓, ¼.
  • Equivalent fractions: Fractions that represent the same value. Created by multiplying or dividing both numerator and denominator by the same number.
  • Simplest form: A fraction where the numerator and denominator share no common factor except 1.
  • Comparing fractions (same denominator): Larger numerator = larger fraction.
  • Comparing fractions (same numerator): Larger denominator = smaller fraction.
  • Brahmagupta’s method for adding/subtracting unlike fractions: cross-multiply to get a common denominator.
  • On a number line, fractions between 0 and 1 divide the segment into equal parts.
📖 Important Terms
NumeratorTop number — how many parts are taken
DenominatorBottom number — how many equal parts the whole is divided into
Unit fractionA fraction with 1 as the numerator
Equivalent fractionsDifferent fractions representing the same value
Simplest formFraction reduced so HCF of numerator and denominator is 1
Like fractionsFractions with the same denominator
Unlike fractionsFractions with different denominators
∑ Formulas & Rules
  • Equivalent fraction a/b = (a×n) / (b×n) for any n ≠ 0 Example: 2/3 = 4/6 = 6/9 = 8/12
  • Simplifying Divide both by HCF: 12/18 → divide by 6 → 2/3
  • Adding unlike fractions (Brahmagupta) a/b + c/d = (ad + bc) / bd Example: 2/3 + 1/4 = (2×4 + 1×3)/(3×4) = 11/12
  • Subtracting unlike fractions a/b − c/d = (ad − bc) / bd
  • Adding like fractions a/n + b/n = (a + b) / n
📐 Important Diagrams

Fraction of a shape: A circle divided into 4 equal parts. Shading 3 parts shows ¾. The denominator (4) is total parts; numerator (3) is shaded parts.

Fraction wall: Rows of equal-length bars divided into 1, 2, 3, 4, 5, ... equal parts. Shows equivalent fractions visually: ½ aligns with 2/4, 3/6, etc.

Number line: Mark 0 and 1, divide into equal segments. For fifths: 0, 1/5, 2/5, 3/5, 4/5, 1. Helps compare and order fractions.

💡 Remember Points

  • To compare unlike fractions, convert to the same denominator first (LCM method or cross-multiply).
  • Among unit fractions, ½ > ⅓ > ¼ > ... — bigger denominator means smaller fraction.
  • Always simplify your final answer to the simplest form.
  • Brahmagupta’s formula works for all fractions — but simplify the result!

⚠ Common Mistakes

  • Adding numerators AND denominators: 1/3 + 1/4 ≠ 2/7. You must find a common denominator first!
  • Thinking bigger denominator means bigger fraction — ⅓ < ½, not greater.
  • Forgetting to simplify: 4/8 should be written as ½.

✏ Figure it Out Sections
  • 1

    Equivalent Fractions

    Understanding and generating equivalent fractions.

    3 Qs
  • 2

    Same Fractional Unit

    Expressing fractions with a common denominator.

    8 Qs
  • 3

    Simplest Form

    Reducing fractions to their simplest form.

    4 Qs
  • 4

    Comparing Fractions

    Ordering and comparing fractions using different methods.

    3 Qs
  • 5

    Adding Fractions

    Adding like and unlike fractions.

    3 Qs
  • 6

    Subtracting Fractions

    Subtracting fractions with same and different denominators.

    3 Qs
Chapter 8
Playing with Constructions
Compass and ruler constructions, rectangle and square properties, diagonals
9FiO Sections
𝒢 Key Concepts
  • A compass is used to draw circles, arcs and mark equal lengths.
  • A ruler (straightedge) draws straight lines and measures lengths.
  • Rectangle properties: Opposite sides are equal, all four angles are 90°.
  • Square properties: All four sides are equal, all four angles are 90°.
  • Every square is a rectangle (but not every rectangle is a square).
  • Diagonals of a rectangle are equal in length.
  • Diagonals of a rectangle bisect each other (cut each other in half).
  • Constructions on dot paper help visualise shapes and their properties.
  • A circle is the set of all points at a fixed distance (radius) from a centre point.
  • Geometric artwork can be created by combining arcs and straight lines systematically.
📖 Important Terms
CompassA tool with two arms for drawing circles and arcs
ArcA part (curve) of a circle
RadiusDistance from centre to any point on a circle
DiameterA line segment through the centre connecting two points on a circle; = 2 × radius
DiagonalA line segment connecting two non-adjacent corners of a polygon
BisectTo divide into two equal parts
Dot paperPaper with evenly spaced dots for drawing shapes accurately
∑ Formulas & Rules
  • Rectangle diagonal property Diagonal 1 = Diagonal 2 (equal in length)
  • Diagonals bisect each other Each diagonal cuts the other into two equal halves
  • Square is a special rectangle Square: l = b, so all rectangle properties apply + diagonals are perpendicular
  • Number of diagonals A polygon with n sides has n(n−3)/2 diagonals Rectangle (4 sides): 4×1/2 = 2 diagonals. Pentagon (5 sides): 5×2/2 = 5 diagonals.
📐 Important Diagrams

Rectangle with diagonals: Draw rectangle ABCD. Diagonals AC and BD cross at point O. AO = OC and BO = OD (bisection). AC = BD (equal diagonals).

Square on dot paper: Connect 4 dots forming a square. All sides span the same number of dots. Tilt the square 45° for a tilted square whose side length involves the Pythagorean theorem.

Circle with compass: Fix one arm at the centre, rotate the pencil arm 360°. All points on the curve are exactly one radius away from the centre.

💡 Remember Points

  • A square has ALL the properties of a rectangle PLUS equal sides and perpendicular diagonals.
  • When constructing on dot paper, count dots carefully — sides may be tilted (not horizontal/vertical).
  • Keep the compass width fixed while drawing an arc — any wobble changes the radius.
  • Diagonals of a square are perpendicular (cross at 90°); rectangle diagonals are NOT.

⚠ Common Mistakes

  • Saying “a rectangle is a square” — it is the other way around: every square is a rectangle.
  • Assuming diagonals of a rectangle are perpendicular — they are equal but NOT necessarily perpendicular (only in a square).
  • Changing the compass width between steps of a construction, leading to inaccurate shapes.

✏ Figure it Out Sections
  • 1

    Artwork

    Creating geometric artwork using constructions.

    3 Qs
  • 2

    Wave Pattern Details

    Analysing and replicating wave patterns.

    3 Qs
  • 3

    Squares on Dot Paper

    Constructing squares of different sizes on dot paper.

    3 Qs
  • 4

    Constructing Rectangles

    Drawing rectangles with given dimensions on dot paper.

    3 Qs
  • 5

    Exploration

    Open-ended geometric exploration activities.

    2 Qs
  • 6

    Breaking Rectangles

    Decomposing rectangles into smaller shapes.

    3 Qs
  • 7

    Complex Constructions

    Multi-step constructions combining various techniques.

    6 Qs
  • 8

    Diagonals

    Properties and constructions involving diagonals of polygons.

    3 Qs
  • 9

    Diagonal Constructions

    Advanced constructions using diagonals.

    1 Q
Chapter 9
Symmetry
Line symmetry, lines of symmetry in shapes, rotational symmetry and paper cutting
4FiO Sections
𝒢 Key Concepts
  • Line symmetry: A shape has line symmetry if it can be folded along a line so both halves match exactly.
  • The fold line is called the line of symmetry (or mirror line).
  • A shape can have 0, 1, 2, or more lines of symmetry.
  • Square: 4 lines of symmetry (2 through midpoints of opposite sides + 2 diagonals).
  • Rectangle: 2 lines of symmetry (through midpoints of opposite sides only).
  • Equilateral triangle: 3 lines of symmetry (each from a vertex to the midpoint of the opposite side).
  • Circle: Infinite lines of symmetry (every diameter is a line of symmetry).
  • A rectangle’s diagonal is NOT a line of symmetry — the two triangles formed are mirror images only if it is a square.
  • Rotational symmetry: A shape looks the same after rotation by less than 360°.
  • Angle of rotation = 360° / n, where n is the number of positions where the shape looks the same.
📖 Important Terms
Line of symmetryA line that divides a shape into two identical mirror halves
Mirror lineAnother name for line of symmetry
Rotational symmetryA shape maps onto itself when rotated by less than 360°
Order of rotationNumber of times a shape maps onto itself in one full turn
Angle of rotationThe smallest angle for the shape to look the same: 360°/n
∑ Formulas & Rules
  • Angle of rotational symmetry Angle = 360° / n Where n = order of rotational symmetry (number of matching positions)
  • Lines of symmetry (common shapes) Square: 4 | Rectangle: 2 | Equilateral triangle: 3 | Circle: ∞
  • Regular polygon with n sides Lines of symmetry = n | Order of rotation = n Regular pentagon: 5 lines, order 5. Regular hexagon: 6 lines, order 6.
ShapeLines of SymmetryRotational OrderAngle
Equilateral triangle33120°
Square4490°
Rectangle22180°
Regular pentagon5572°
Regular hexagon6660°
Circleany angle
Parallelogram (non-rect.)02180°
📐 Important Diagrams

Lines of symmetry of a square: Draw a square. It has 4 lines: one horizontal (through midpoints of top and bottom), one vertical (through midpoints of left and right), and two diagonals.

Paper cutting symmetry: Fold paper along the line of symmetry, cut a shape, unfold. The result is symmetric about the fold line. Predicting the unfolded shape is a key skill.

Rotational symmetry of a windmill: A 4-bladed windmill looks the same every 90° turn. Order = 4, angle = 90°.

💡 Remember Points

  • A parallelogram (that is not a rectangle) has rotational symmetry but NO line symmetry.
  • A shape can have line symmetry only, rotational only, both, or neither.
  • The diagonal of a rectangle is NOT a line of symmetry — this is a very common exam question!
  • For paper-cutting problems: the fold line is always a line of symmetry of the final shape.

⚠ Common Mistakes

  • Thinking a rectangle’s diagonal is a line of symmetry — fold along it and the halves do NOT match.
  • Confusing order of rotation with angle of rotation — they are related (360/n) but different things.
  • Forgetting that every shape maps onto itself after a 360° rotation — that doesn’t count as rotational symmetry.

✏ Figure it Out Sections
  • 1

    Lines of Symmetry

    Identifying lines of symmetry in shapes and figures.

    2 Qs
  • 2

    Punching Game and Paper Cutting

    Predicting outcomes of punching holes and cutting folded paper.

    13 Qs
  • 3

    Rotational Symmetry

    Understanding rotation and order of rotational symmetry.

    3 Qs
  • 4

    Advanced Symmetry

    Combining line and rotational symmetry concepts.

    11 Qs
Chapter 10
The Other Side of Zero
Integers, negative numbers, number line operations, token model and real-world applications
14FiO Sections
𝒢 Key Concepts
  • Integers include all positive numbers, zero and negative numbers: ..., −3, −2, −1, 0, +1, +2, +3, ...
  • On a number line, numbers increase to the right: −3 < −2 < −1 < 0 < 1 < 2 < 3.
  • Positive integers are to the right of 0; negative integers are to the left.
  • Zero is neither positive nor negative.
  • Addition rules: Same signs → add magnitudes, keep the sign. Different signs → subtract magnitudes, take sign of larger.
  • Subtracting a negative = adding the positive: a − (−b) = a + b.
  • Additive inverse: For every integer a, there exists −a such that a + (−a) = 0.
  • Token model: Green token = +1, Red token = −1. A green-red pair = zero pair (cancels out).
  • Real-world contexts: temperature (below zero), altitude (below sea level), banking (debits).
📖 Important Terms
IntegerAny positive whole number, negative whole number, or zero
Positive integerNumbers greater than zero: +1, +2, +3, ...
Negative integerNumbers less than zero: −1, −2, −3, ...
Additive inverseThe number that, when added to a given number, gives 0
Zero pairA pair of +1 and −1 tokens that cancel each other
MagnitudeThe size of a number regardless of sign (absolute value)
∑ Formulas & Rules
  • Adding same signs (+a) + (+b) = +(a+b)   |   (−a) + (−b) = −(a+b) (+3)+(+5) = +8  |  (−3)+(−5) = −8
  • Subtracting a negative a − (−b) = a + b 5 − (−3) = 5 + 3 = 8
  • Additive inverse a + (−a) = 0 7 + (−7) = 0  |  −4 + (+4) = 0
  • Ordering integers On the number line: further right = greater −5 < −2 < 0 < 3 < 7
  • Token model Green (+1) + Red (−1) = 0 (zero pair cancels)
📐 Important Diagrams

Number line with integers: A horizontal line with 0 at centre, positive integers marked at equal intervals to the right (+1, +2, +3, ...) and negative integers to the left (−1, −2, −3, ...). Arrows show the line extends infinitely both ways.

Building/lift model: Ground floor = 0, floors above = positive (+1, +2, +3), basement levels = negative (−1, −2, −3). Going up = adding positive, going down = adding negative.

Token model: Green circles represent +1, red circles represent −1. To show +3, use 3 green tokens. To show −2, use 2 red tokens. To add (+3)+(−2): place all tokens, cancel 2 zero pairs, 1 green remains = +1.

Temperature/altitude diagram: A vertical number line with sea level (or 0°C) in the middle. Positive values above, negative values below. Shows real-world meaning of integers.

💡 Remember Points

  • −1 is greater than −100 — on the number line, −1 is further to the right.
  • Subtracting a negative is the same as adding: “minus a minus is a plus.”
  • Zero is the additive identity: any number + 0 = that number.
  • In the token model, you can always add zero pairs without changing the value — useful for subtraction.
  • Credit = positive, Debit = negative in banking context.

⚠ Common Mistakes

  • Thinking −5 > −2 because 5 > 2 — with negatives, the number closer to 0 is greater.
  • Writing a − (−b) = a − b instead of a + b — subtracting negative ADDS.
  • Forgetting that 0 is an integer — it is neither positive nor negative, but it IS an integer.

✏ Figure it Out Sections
  • 1

    Lift Model Addition — Going Up

    Adding positive integers using a lift/elevator model.

    3 Qs
  • 2

    Lift Model Addition — Going Down

    Adding negative integers — going below ground floor.

    4 Qs
  • 3

    Comparing Integers

    Ordering integers on a number line, greater than and less than.

    4 Qs
  • 4

    Subtraction Using Floors

    Subtracting integers using the building floors model.

    10 Qs
  • 5

    Number Line

    Representing and operating with integers on a number line.

    4 Qs
  • 6

    Large Number Operations

    Adding and subtracting larger integers.

    8 Qs
  • 7

    Token Model Addition

    Using positive and negative tokens to model addition.

    2 Qs
  • 8

    Token Model Subtraction Part 1

    Subtracting integers using the token model.

    2 Qs
  • 9

    Token Model Subtraction Part 2

    Advanced token model subtraction with cancellation.

    2 Qs
  • 10

    Banking Context

    Credits, debits and account balances using integers.

    3 Qs
  • 11

    Geography Cross-Section

    Altitude and depth — above and below sea level.

    5 Qs
  • 12

    Temperature

    Positive and negative temperatures, rises and falls.

    2 Qs
  • 13

    Integer Grids and Magic Squares

    Filling grids and magic squares with integers.

    5 Qs
  • 14

    Amazing Number Grid

    Exploring patterns in an extended number grid with negatives.

    7 Qs