Question

What is the gcf of 25 and 90

Answer 1

less nerdy answer is

25: 1,5,25

90: 1,2,3,5,6,9,10,15,18,30,45,90

Answer 2

25 = 5^2
90 = 2 . 3 . 3 . 5

GCF is not as greedy as LCM.
GCF is just on a diet, so it takes the same number and the smallest amount.

25 and 90 both have 5.
5^2 or 5 ?
Take the smaller one.
GCF = 5