NCERT Ganita Prakash, Class 8, textbook pages 146–182 (Part 1)

How to teach Class 8 Maths Chapter 5, Number Play, at home

Divisibility, consecutive sums and digit puzzles, taught with things you already have at home: a 30-minute activity, a game for the week, a 5-day plan and the mistakes to watch for.

n + (n+1) + (n+2)= 3n + 3 = 3(n + 1)always a multiple of 3

NCERT Class 8 Maths Chapter 5 Number Play: what it teaches

Your child investigates sums of consecutive numbers, divisibility patterns, digital roots, and puzzles where algebra explains why a trick works.

Why it matters later. Explaining patterns with algebra is the start of proof in Class 9 and 10.

See it: this chapter in pictures

9 = 4 + 5 = 2 + 3 + 410 = 1 + 2 + 3 + 416 = ? no way!
Powers of 2 have no consecutive sum.
486 → 4 + 8 + 6 = 18→ 1 + 8 = 9digital root 9: divisible by 9
Digital roots reveal divisibility by 9.
2,34,568÷4: last two digits 68 ✓÷8: last three 568 ✓
Look only at the last digits.

You need

  • paper and pencil
  • number cards
  • a calculator for checking

Tonight’s 30 minutes

  1. Which numbers can be written as a sum of consecutive numbers? (Try 9, 10, 16.)
  2. Why is the sum of 3 consecutive numbers always a multiple of 3? (n + (n+1) + (n+2) = 3n + 3.)
  3. Digital root: add digits until one digit remains. Check multiples of 9.
  4. Test divisibility of a 6-digit number by 4, 8 and 11.

Words to use

  • consecutive
  • divisible
  • digital root
  • multiple
  • proof
  • pattern

Watch for

  • Believing a pattern from a few examples. Use letters to show it works for every number.
  • Mixing up divisibility tests. Write the rule next to each test.

What it sounds like at home

A short example of the conversation. Your words will differ; the questions are what matter.

YouIs the sum of 3 consecutive numbers always a multiple of 3?

Your childn + n+1 + n+2 = 3(n+1), yes!

A game for this week: Consecutive challenge

  1. Pick a number from 10 to 50.
  2. Players find ways to write it as a sum of consecutive numbers.
  3. Each way scores.
  4. Discuss numbers with no way.

A 5-day plan, 30 minutes a day

  1. Day 1Consecutive sums.
  2. Day 2Algebra proofs of patterns.
  3. Day 3Digital roots.
  4. Day 4Divisibility tests.
  5. Day 5Consecutive challenge.

Everyday moments to practise

  • Page numbers adding up.
  • Cricket scoring patterns.
  • Calendar tricks.
  • Bill checks.

Quick check

Ask these at the end of the week. Tap to see the answer.

Sum of 7, 8, 9?

24, a multiple of 3.

Digital root of 486?

9.

Can 16 be written as a sum of consecutive numbers?

No (powers of 2 can’t).

Ready for the next chapter when your child…

  • Explains patterns with algebra.
  • Uses divisibility tests.
  • Finds digital roots.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Ganita Prakash (Class 8). See the full Class 8 parent guide for every chapter.

Questions parents ask

Why can’t powers of 2 be sums of consecutive numbers?

Such sums always have an odd factor greater than 1.

What is a digital root?

The single digit left after repeatedly adding digits.

Why use algebra in number play?

To prove a pattern always works.