GCF
factor them and find the group of factors common to both
example
18 and 24
18=233
24=2223
common group is 23 or 6
gcf=6
LCM=least common multiupule
means smallest number that both can go into evenly
factor them and make a group that includes both of them, if you have repeats, replace them
18 and 24
18=233
24=2223
LCM=2223*3=72
