How do you find the Lcm of 20,24?

Question

5259 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-11-08T19:47:22

120

one quick way is to use the relation

#GCFxxLCM=axxb#

#GCF(20,24)=4#

#LCMxx4=20xx24#

#LCM=(20xx24)/4#

#LCM=(cancel(20)^5xx24)/cancel(4#

#=120#

Answer 2 · 2016-11-12T22:01:46

A bit of a cheat method.

Lowest common multiple is 120

Any multiple of 20 ends with the digit 0

So all we need to do is determine the first multiple of 4 from 24 that ends with the digit 0.

#1xx4 = 4 color(red)(" "larr "Fail")#
#2xx4=8color(red)(" "larr "Fail")#
#3xx4=12color(red)(" "larr "Fail")#
#4xx4=16color(red)(" "larr "Fail")#

#5xx4=20 color(green)(" "larr "Works")#

Thus we have #" "5xx24= 120#

Lowest common multiple is 120