Sender: John

Name 2 different pairs of numbers whose GCF is 28.

First write the prime factorization of 28.

One way to produce a pair of numbers whose GCF is 28 is to multiply 28 by a primes that do not appear in the prime factorization of 28. For example 5 and 13 are primes that do not appear in the prime factorization of 28 and hence 28 x 5 and 28 x 13 have 28 as their GCF.