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Class 8 Maths — 14 skills

Everything a Class 8 child (ages 13–14) practises in BeadBop School Maths, aligned to NCERT. Each skill below has a one-line explanation and sample questions with answers — practise them free in the app with step-by-step help.

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Numbers

Rational numbers

Work with fractions that can be negative: same denominator to add, multiply tops and bottoms to multiply. The additive inverse of 3/5 is −3/5; the multiplicative inverse (reciprocal) of −2/7 is −7/2.

Builds on: Add rational numbers, Multiply and divide integers

Try it:

  1. (−2/5) + 7/2 = ? (simplest form) → 31/10
  2. What is the additive inverse of 3/4? → −3/4

Squares and square roots

Pair up equal prime factors: 324 = (2 × 2) × (3 × 3) × (3 × 3), so √324 = 2 × 3 × 3 = 18. For any m, 2m, m² − 1 and m² + 1 form a Pythagorean triplet.

Builds on: Exponents and powers, Prime factorisation, Pythagoras theorem

Try it:

  1. Using prime factorisation, find √441. → 21
  2. Using prime factorisation, find √1764. → 42

Cubes and cube roots

A cube is a number times itself three times: 6³ = 216. For a cube root, group equal prime factors in threes: 1728 = (2×2×2)(2×2×2)(3×3×3), so ∛1728 = 2 × 2 × 3 = 12.

Builds on: Squares and square roots, Prime factorisation

Try it:

  1. Find ∛512. → 8
  2. Find ∛6859. → 19

Negative exponents and standard form

A negative power means “one over”: 2⁻³ = 1/2³ = 1/8. Standard form writes a number as (1 to 10) × a power of 10: 0.00042 = 4.2 × 10⁻⁴.

Builds on: Exponents and powers

Try it:

  1. Find the value of (5/2) −1 . → 2/5
  2. Write 0.002 in standard form. → 2 × 10<sup>−3</sup>

Algebra

Linear equations in one variable

Collect the x-terms on one side and the numbers on the other, then divide. 5x − 3 = 2x + 9 → 3x = 12 → x = 4.

Builds on: Two-step equations

Try it:

  1. One number is 6 more than another. Their sum is 58. What is the smaller number? → 26
  2. Solve: 5x − 18 = 7x − 30 → 6

Algebraic identities

(a + b)² = a² + 2ab + b², (a − b)² = a² − 2ab + b², (a + b)(a − b) = a² − b². So 103² = 100² + 2×100×3 + 3² = 10609 and 98 × 102 = 100² − 2² = 9996.

Builds on: Simplify algebraic expressions, Squares and square roots

Try it:

  1. Expand (p + 8)². → p² + 16p + 64
  2. Use an identity to find 8 × 12. → 96

Factorisation

Take out the common factor first: 6x² + 9x = 3x(2x + 3). Use a² − b² = (a − b)(a + b). For x² + bx + c, find two numbers that multiply to c and add to b: x² + 7x + 12 = (x + 3)(x + 4).

Builds on: Algebraic identities

Try it:

  1. Factorise: 9y² − 16 → (3y − 4)(3y + 4)
  2. Factorise fully: 30x² + 42x → 6x(5x + 7)

Shapes & patterns

Angles of polygons

Interior angles of an n-sided polygon add to (n − 2) × 180°. The exterior angles always add to 360°, so each exterior angle of a regular polygon is 360° ÷ n.

Builds on: Exterior angle of a triangle, Complementary and supplementary angles

Try it:

  1. What is each interior angle of a regular polygon with 8 sides (in degrees)? → 135
  2. What is each exterior angle of a regular polygon with 30 sides (in degrees)? → 12

Introduction to graphs

A point (x, y) means go x across, then y up. Points on a straight-line graph change by the same amount each step, so you can continue the pattern.

Builds on: Linear equations in one variable

Try it:

  1. A straight-line graph of distance (km) against hours passes through (2, 11) and (3, 16). What is the distance (in km) after 8 hours? → 41
  2. The point (4, k) lies on the line y = 2x − 6. Find k. → 2

Word problems

Direct and inverse proportion

Direct: both go up together, so the ratio stays the same (more pens cost more). Inverse: one goes up as the other goes down, so the product stays the same (more workers take fewer days).

Builds on: Proportion, The unitary method

Try it:

  1. 4 pumps empty a pond in 11 hours. How many hours will 2 pumps take? → 22
  2. 10 pumps empty a pond in 20 hours. How many hours will 25 pumps take? → 8

Money & time

Discount, GST and compound interest

Discount comes off the marked price; GST is added on top. Compound interest for 2 years: Amount = P × (1 + R/100)², and CI = Amount − P.

Builds on: Percentage increase and decrease, Profit and loss per cent, Simple interest

Try it:

  1. A phone cover costs ₹2,500 before GST. GST is 28%. How much do you pay in total? → ₹3,200
  2. A jacket marked ₹600 is sold at a discount of 50%. What is the selling price? → ₹300

Measurement

Mensuration

Trapezium area = ½ × (sum of parallel sides) × height. Cuboid: volume = l × b × h, surface area = 2(lb + bh + hl). Cube: 6a² and a³. Cylinder: volume = πr²h, curved surface = 2πrh.

Builds on: Circumference and area of a circle, Perimeter of polygons

Try it:

  1. A cylinder has radius 14 cm and height 15 cm. Find its volume (in cm³). (π = 22/7) → 9240
  2. A cuboid is 7 cm × 11 cm × 7 cm. Find its total surface area (in cm²). → 406

Data handling

Probability of simple events

Probability = favourable outcomes ÷ total outcomes. A die has 6 outcomes; the chance something does NOT happen is 1 − the chance it does.

Builds on: Simple probability

Try it:

  1. A fair die is rolled once. What is the probability of getting an odd number? → 1/2
  2. A spinner has 5 equal parts and 1 of them are blue. What is the probability the spinner stops on blue? → 1/5

Data handling: pie charts and groups

In a pie chart, angle = (part ÷ total) × 360°. In grouped data like 10–20, the class size is the gap 20 − 10 = 10.

Builds on: Mean and range, Probability of simple events

Try it:

  1. A pie chart shows how 120 families travel. The sector for “bus” has an angle of 45°. How many families travel by bus? → 15
  2. A pie chart shows how 60 families travel. The sector for “bus” has an angle of 30°. How many families travel by bus? → 5

Questions parents ask

What maths does a Class 8 child learn?

In Class 8 (ages 13–14) BeadBop covers 14 skills: Rational numbers, Linear equations in one variable, Angles of polygons, Squares and square roots, Cubes and cube roots, Negative exponents and standard form, Direct and inverse proportion, Discount, GST and compound interest, Algebraic identities, Factorisation, Mensuration, Introduction to graphs, Probability of simple events, Data handling: pie charts and groups.

How can my child practise Class 8 maths at home?

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