NCERT Book Class 6 Mathematics Chapter 5 Prime Time

5 PRIME TIME

5.1 Common Multiples and Common Factors

Idli-Vada Game
Children sit in a circle and play a game of numbers.
One of the children starts by saying ‘1’. The second
player says ‘2’, and so on. But when it is the turn of 3, 6,
9, … (multiples of 3), the player should say ‘idli’ instead
of the number. When it is the turn of 5, 10, … (multiples
of 5), the player should say ‘vada’ instead of the number.
When a number is both a multiple of 3 and a multiple
of 5, the player should say ‘idli-vada’! If a player makes
any mistake, they are out.
The game continues in rounds till only one person
remains.
For which numbers should the players say ‘idli’
instead of saying the number? These would be 3, 6, 9,
12, 18, … and so on.
For which numbers should the players say ‘vada’?
These would be 5, 10, 15, 20, … and so on.
Which is the first number for which the players
should say, ‘idli-vada’? It is 15, which is a multiple of 3,
and also a multiple of 5. Find out other such numbers
that are multiples of both 3 and 5. These numbers are
called _____________________________.

Chapter 5_Prime Time.indd 107 13-12-2024 15:59:16