The answer is 20 because the multiple of a number can not be less than the number itself so we can cross out the option 2 and 4 because they are both less than 10. We can then check if 20 and 40 fit the requirements of being a multiple of both 10 and 4. They both fit but it asks for the LEAST common multiple and because 20 is smaller than 40, we can find our answer to be C, 20.
