How do you determine the least common multiple (LCM) of 4 and 5?

To determine the least common multiple (LCM) of two numbers, you look for the smallest positive integer that is a multiple of both numbers. In this case, the multiples of 4 are 4, 8, 12, 16, 20, and so on, while the multiples of 5 are 5, 10, 15, 20, 25, etc. The smallest common multiple shared by both lists is 20.

By systematically identifying the multiples, you can observe that 20 is the first number that appears in both sequences, confirming that it is the least common multiple. This approach effectively identifies the LCM through enumeration and comparison of multiples rather than through operations like addition, multiplication, or simply choosing the larger number, which do not guarantee the smallest common multiple.