What are the least common multiples of 7,14 and 21?

3 Answers
EZ as pi
Mar 3, 2018

#LCM = 42#

Explanation:

Every number is the lowest multiple of itself, but there is only ever one lowest (least) common multiple of 2 or more numbers.

For the LCM of #7, 14 and 21#, we can ignore #7# completely because it is a factor of the other two numbers, so will automatically be factor of every one of those multiples.

Write each number as the product of the prime factors:

#" "7 = color(white)(xxxxxx)7#
#" "14 = 2color(white)(w.w)xx 7#
#" "21 = ul(" "3xx7)#

#LCM = 2xx3xx7 =42#
#HCF = color(white)(xxxxxx)7#

Josie
Mar 3, 2018

42

Explanation:

Multiples of 7: 7, 14, 21, 28, 35, 42, 49...
Multiples of 14: 14, 28, 42, 56...
Multiples of 21: 21, 42, 63...

Deepesh Pandey · Aviv S.
Mar 3, 2018

It is 42 !!

Explanation:

Least common multiple simply means the "smallest" number which is common in the multiplication tables of the given set of numbers.

Hence , for 7,14,and 21 it will be 42 as it is the smallest number which is common in the tables of the given numbers .

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