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

To find the least common multiple (LCM) of 4 and 5, we start by identifying the multiples of each number.

The multiples of 4 are:

4, 8, 12, 16, 20, 24, ...

The multiples of 5 are:

5, 10, 15, 20, 25, ...

Next, we look for the smallest multiple that appears in both lists. From the lists, the first common multiple is 20. This means that the LCM of 4 and 5 is indeed 20.

It's worth noting that the LCM is the smallest number that is a multiple of both numbers, and since 4 and 5 do not share any factors other than 1, their LCM can also be found by multiplying them together (4 × 5 = 20) and then dividing by their greatest common divisor (which is 1). Since there are no common factors, we simply get 20 as the result.

Therefore, the least common multiple of 4 and 5 is 20.