what is the gcf of 72 and 90

The greatest common factor (GCF) of 72 and 90 is 18. To find the GCF of two numbers, we need to factor each number and choose the greatest factor that exactly divides both numbers. The factors of 72 are 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, and 72, while the factors of 90 are 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, and 90. We can see that the greatest factor that divides both 72 and 90 is 18, so the GCF of 72 and 90 is 18. Another way to find the GCF is to use prime factorization. The prime factorization of 72 is 2 × 2 × 2 × 3 × 3, while the prime factorization of 90 is 2 × 3 × 3 × 5. The common prime factors are 2, 3, and 3, so the GCF is 2 × 3 × 3 = 18.