Answer: is 15
GCF of 45 and 60 is the largest possible number that divides 45 and 60 exactly without any remainder. The factors of 45 and 60 are 1, 3, 5, 9, 15, 45 and 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60 respectively. There are 3 commonly used methods to find the GCF of 45 and 60 Euclidean algorithm, long division, and prime factorization.