Basic College Mathematics (9th Edition)

Published by Pearson
ISBN 10: 0321825535
ISBN 13: 978-0-32182-553-7

Chapter 3 - Adding and Subtracting Fractions - Summary Exercises - Operations with Fractions - Page 236: 38

Answer

84

Work Step by Step

The least common multiple (LCM) of a group of numbers is the smallest number that is divisible by all of the numbers in the group. In order to find the LCM of 4, 12, and 21, we can find the smallest multiple of 21 that is divisible by both 4 and 12. 21- not divisible by either 42- not divisible by either 63- not divisible by either 84- divisible by both $84\div4=21$ $84\div12=7$ Therefore, the LCM of 4, 12, and 21 is 84.
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