Chapter 3: Number PlayClass 6 Mathematics — summary, notes, extra questions & NCERT solutions

Summary

This chapter explores numbers through games, puzzles and patterns, building computational thinking. It opens with a line of children each saying the number of taller neighbours they have, showing how numbers convey information. Supercells are cells whose number is larger than all neighbouring cells; students fill grids to maximise supercells. The chapter places large numbers on number lines and counts how many 1-, 2-, 3-, 4- and 5-digit numbers exist (\(9, 90, 900, 9000, 90000\)). It studies digit sums, palindromes (numbers that read the same both ways, such as 575 or 12321), and the reverse-and-add method. A highlight is the Kaprekar constant: repeatedly making the largest minus the smallest number from a 4-digit number always reaches 6174. Clock and calendar number patterns, mental-math methods, and number-pattern sums are covered. The famous unsolved Collatz conjecture is introduced \u2014 halving even numbers and applying \(3n+1\) to odd numbers always seems to reach 1. The chapter ends with simple estimation and winning strategies for number games like reaching 21.

Key terms

Extra questions & answers

Think about various situations where we use numbers.

Try answering the questions below and share your reasoning.

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Complete Table 2 with 5-digit numbers whose digits are ‘1’, ‘0’, ‘6’, ‘3’, and ‘9’ in some order. Only a coloured cell should have a number greater than all its neighbours.

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Find out how many numbers have two digits, three digits, four digits, and five digits.

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Digit Detectives

Write all possible 3-digit palindromes using these digits.

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Puzzle time

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