The greatest common factor (GCF) of 30 and 48 is 6. There are several methods to find the GCF of two numbers, including long division, prime factorization, and Euclidean algorithm. One way to find the GCF of 30 and 48 is to list the factors of each number and find the largest factor that they have in common. The factors of 30 are 1, 2, 3, 5, 6, 10, 15, and 30, while the factors of 48 are 1, 2, 3, 4, 6, 8, 12, 16, 24, and 48. The largest factor that they have in common is 6, so the GCF of 30 and 48 is 6. Another way to find the GCF is to use prime factorization. The prime factorization of 30 is 2 x 3 x 5, while the prime factorization of 48 is 2 x 2 x 2 x 2 x 3. The common prime factors are 2 and 3, so the GCF is 2 x 3 = 6.