My teacher divided his class into groups of 8 on Monday, 10 on Tuesday and 4 on Wednesday. What is the least possible number of children in his class?

The LCM is 40.

To find the least possible number of children in the class, we need to determine the least common multiple (LCM) of the group sizes.

First, let's find the LCM of 8, 10, and 4:

Multiples of 8: 8, 16, 24, 32, 40, 48, 56, 64, ...
Multiples of 10: 10, 20, 30, 40, 50, 60, 70, ...
Multiples of 4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, ...

To find the LCM, we look for the smallest number that appears in all three lists. In this case, the number 40 is the least common multiple.

Therefore, the least possible number of children in the class is 40.