Davey and Charlie shared half a box of crackers.  They each had 20 crackers.  How many crackers did the box have when it was full.
I did 20 times 20 because it said they each had 20 crackers and there are only 2 people.  I got 40.  40 is half the box.  So I did 40 times 2 because the question wanted the whole box.  The had 80 crackers when it was full.