20
7
More Recipe Math
Lamar also needs to bake the chocolate cake. He’s decided to invite more people to drop by for
dessert, so he wants to be sure the cake is big enough to serve 20 people. The recipe he wants
to use, though, will only serve 8. How can he figure out how to make a cake big enough for that
many people?
He has a couple of options. He could divide 20 by 8, which equals 2 with a remainder of 4.
Since 4 is half of 8, this is the same thing as 2½.
20 ÷ 8 = 2½
Now he will need to multiply each of the ingredients in his recipe by 2½.
But Lamar wants to make it easier for himself. He decides to triple the recipe instead. This
means he will multiply all themeasurements by 3 instead. Multiplying by a whole number is easier.
Now he can cut the cake into slightly bigger slices and still have enough for everyone. Or he
can have 4 pieces left over to keep for himself !
Fill in the chart on the next page to find out the amounts he’ll need for each ingredient if he
triples the recipe.
