LCM = least common multiple
The lowest number that is a shared factor between the given values.
You use LCM for both of these problems.
For the first:
7: 7, 14, 21, 28…
14: 14, 28, 42…
The smallest shared multiple is 14, answer #1.
For the word problem, the same thing. Harry needs to buy enough supplies for there to be an equal 1:1 ratio of Pattie’s to buns.
So list out the factors:
12: 12, 24, 36, 48, 60, 72…
20: 20, 40, 60, 80, 100…
So the LCM would be 60, but there’s one more step to get the answer. You have to divide
# of patties per box/LCM(60)
and
# of buns per box/LCM(60)
So the problem stated there are 12 buns per package:
12 buns/60 = 5 packs of buns
And the patties:
20 patties/60 = 3 packs of patties
So they need to buy 5 packs of buns and 3 packs of patties, answer #3.
