A **factor** is an integer that will divide into another integer without leaving a remainder.

To find all the factors of a number, work out which other numbers will divide into that number.

Factors always work in pairs (because they have to be multiplied by something else). But sometimes it might be multiplied by itself eg the pairs of factors for 9 are 1 x 9 and 3 x 3.

The number itself, and the number 1, are always factors.

What are the factors of 32?

The pairs are 1 x 32, 2 x 16 and 4 x 8.

Answer: 1, 2, 4, 8, 16 and 32

What factors do 32 and 20 have in common?

For 32: 1, 2, 4, 8, 16, 32. For 20: 1, 2, 4, 5 and 20. The numbers that are in both lists are 1, 2 and 4.

Answer: 1, 2 and 4

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