What is the least common multiple (LCM) of 4 and 5?

To find the least common multiple (LCM) of two numbers, we need to determine the smallest positive integer that is divisible by both numbers. In this case, we are looking at the numbers 4 and 5.

The multiples of 4 are: 4, 8, 12, 16, 20, 24, and so forth.

The multiples of 5 are: 5, 10, 15, 20, 25, and so forth.

Next, we identify the common multiples from both lists. The smallest number that appears in both lists is 20. Thus, 20 is the least common multiple of 4 and 5.

The LCM can also be computed using the formula involving the greatest common divisor (GCD):

[ \text{LCM}(a, b) = \frac{|a \times b|}{\text{GCD}(a, b)} ]

For 4 and 5, the GCD is 1 since they have no common factors other than 1. Therefore, the calculation is:

[ \text{LCM}(4, 5) = \frac{|4 \times 5|}{\text{GCD