What is the least common multiple of 9, 18 , and 21?

1 Answer
MeneerNask
Apr 7, 2016

We first factor each of them into primes:

Explanation:

#9=3xx3#
#18=2xx3xx3#
#21=3xx7#

Now we take all prime factors to their highest degree that we find in the numbers, so we have one #2#, two #3#'s and one #7#:

Answer:
#2xx3xx3xx7=126#

Check :
#126div9=14=2xx7#
#126div18=7#
#126div21=6=2xx3#
And there is no common factor between the three of them.

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