I understand what a prime factor is, but in the factoring drill, the same number is often repeated. For example, for 56, it lists 2,2,2,and7. Why does it list 2 3 times?

There are two terms at work here.

The prime factorization of 56 is 2 2 2 7
The prime factors of 56 are 2 2 2 7
The unique prime factors of 56 are 2 and 7

In a typical GMAT problem, you'll know which they're seeking and be able to answer the question appropriately.

Hope this helps!

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