Question

Choose all the numbers that are common multiples of 3 and 12.

Answer 1

Answers: 48 and 72

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Explanation:

The number 12 is a multiple of 3 because 3*4 = 12.

So when looking for common multiples of 3 and 12, we simply need to look at multiples of 12.

The multiples of 12 are:

• 12, 24, 36, 48, 60, 72, 84, 96, 120, ...

We see that 48 and 72 are on the list. The values 21, 27, 63, 81 are not on the list, so cross them out.

Now we could keep that list of multiples going to see if 844 is on there or not. A better method is to divide 844 over 12. If we get a whole number, then it's a multiple of 12.

844/12 = 70.333 approximately.

This shows that 844 is not a multiple of 12. So we cross 844 from the list.

Only 48 and 72 are multiples of 12 (and also multiples of 3).