Question 1 What is the greatest common factor of 6, 12, and 25? Answer 1 The GCF is 1. Explanation: Prime factorize each number: 6 = 2 × 3 2×3 12 = 2 2 × 3 2 2 ×3 25 = 5 × 5 5×5 There are no common prime factors, so the GCF is 1. Question 2 How do you find the GCF of 24 and 42? Answer 1 To find the GCF of 24 and 42: List the factors of each number: Factors of 24: 1, 2, 3, 4, 6, 8, 12, 24 Factors of 42: 1, 2, 3, 6, 7, 14, 21, 42 The highest common factor is 6. Result: 6 Question 3 How do you find the GCF of 28 and 36? Answer 1 List the factors of each number: Factors of 28: 1, 2, 4, 7, 14, 28 Factors of 36: 1, 2, 3, 4, 6, 9, 12, 18, 36 The highest common factor is 4. Result: 4 Question 4 What is the greatest common factor of 180 and 225? Answer 1 The GCF is 45. Question 5 How do you find the least common multiple of 10, 2, and 15? Answer 1 List multiples to find the smallest common multiple: Multiples of 10: 10, 20, 30, 40, ... Multiples of 2: 2, 4, 6, 8, 10, 12, ..., 30, ... Multiples of 15: 15, 30, 45, ... The first common multiple of all three numbers is 30. Result: 30