Find the least common multiple for 4 and 5

To find the least common multiple (LCM) of two numbers, we need to find the smallest number that is a multiple of both numbers.

The multiples of 4 are: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, ...

The multiples of 5 are: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, ...

We can see that the smallest number that is a multiple of both 4 and 5 is 20.

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