What is the gcf for 7 and 42?

Answer 1

The answer is 1 because 7 is a Prime number which means that it's only factors are 1 and itself which is 7.

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That is just a rubbish answer. The key is not whether one of the numbers is prime but whether the numbers in the set are co-prime.

GCF(7, 42) = 7.

Although 7 is a prime and divides itself, it also divides 42.