GCSE(F)

Multiples of a number can be written out in ascending order:

the multiples of 12 are 12, 24, 36, 48, 60, ...

Multiples of one number can be shared by another. The first 6 multiples of 10 are:

10, 20, 30, 40, 50, 60 and

the first 6 multiples of 15 are:

15, 30, 45, 60, 75, 90.

Common multiples are 30 and 60 as they appear in both lists.

1. What are the first 5 multiples of 20?

Answer: 20, 40, 60, 80, 100

Add 20 to 20; then add further 20s to the answer until there are 5 numbers.

2. What are the common multiples shared by the first 6 multiples of 12 and of 16?

Answer: 48

12 has multiples of: 12, 24, 36, 48, 60, 72

16 has multiples of: 16, 32, 48 ,64, 80, 76

Only 48 is shared in the first 6 multiples.

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