How do you find the LCM for 9 and 21?

Answer 1

It is not possible to give a sensible answer to this question. 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!

Answer 2

Factor them.
3 x 7 = 21
2 x 2 x 3 x 5 = 60
Combine the factors, eliminating duplicates.
2 x 2 x 3 x 5 x 7 = 420, the LCM

Answer 3

You need at least two numbers to find an LCM.

Answer 4

By multiplying the the highest prime numbers which are 3 squared and 7 = 63

Answer 5

By comparing its multiples to the multiples of another number.

Answer 6

The LCM is 60.

Answer 7

20 and 30 have an LCM of 60.

Answer 8

LCM of 12 and 60 is 60.

Answer 9

42