How to find GCF and LCM
LCM
This is a fast simple way to find the lowest common multiple or the LCM that I will demonstrate now.
step 1
Identify your numbers and draw an upside down division line around them.
step 2
next find a factor that they have in common and write is to the left of the line from earlier.
(mine just so happened to be 9, but yours doesn’t.)
Divide your two numbers by that factor until you get a prime number and then promptly circle all numbers on the outer rim.
step 3
Multiply your newly circled numbers and it should give you the lowest common multiple/LCM.
GCF
Next, finding the greatest common factor between numbers has always been a pain so here’s a solution I found.
step 1
recognise your numbers and divide them with your answer including a remainder if needed. (Don’t forget to always put the smaller number on the left to avoid numbers less than one.)
step 2
once you’ve done that, bring the number on the right and bring it below the larger number on the left and then take the remainder and bring it below the smaller number on the right.
repeat this until you are left without a remainder.
step 3
whatever number the last remainder was, that will be your greatest common factor or GCF.
this process does not have a set amount of times you should get a remainder, simply keep dividing until you are left without a remainder.
