How do you LCM 7 21 and 28?

Answer 1

2 x 11 = 22

2 x 2 x 7 = 28

Select the highest amount of each factor.

2 x 2 x 7 x 11 = 308, the LCM

Answer 2

Find a number that they all go into. The first one you'll come to is 84.

Answer 3

You cannot. The least common multiple (LCM) refers to a multiple that is COMMON to two or more numbers. You have only one number in the question! The least multiple of a number is itself.