Tonights math homework...increasing cupcake recipes!

Math Homework

The students know how to 'do' double digit multiplication. Still, I want them to understand 'what' is going on when they are multiplying factors. When we use the standard algorithm to solve a double digit problem, I've noticed students think of the numbers as 'ones' rather than tens and ones. For example, 25 X 13....

25

X 13

75

250

325

Most students would say they solved this problem by multiply 5 X 3, carry the 1, multiply 3 X 2 then add 1...go to the next line. Add a 0 or an X. Multiply 1X5 then 1X2. Then add both.

When we think about the numbers having value, solving the problem changes.

25X3 + 25X10 = 325

So today we took notes on the different strategies we could think of when solving double digit multiplication. This will become important because for our Cupcake Wars we will be asked as bakers to increase recipes so we can serve more people. Having an understanding of what is truly going on when we multiply double digits will help us to ensure an answer is reasonable. We don't want to come up short or try to make too many and find we don't have enough ingredients.

Homework:

Use the number of servings in your own cupcake recipe or use 12 servings.

How many 'times' will you have to increase your recipe to serve:

a party of 54

a school party of 100

a Manatee game of 850.

All people get one cupcake. You can have a little more but not too much more (so the remainder should be less than the original serving size).

The key word is 'times'. What number X (your recipe's serving size) will have a product that is at or slightly over the amount of cupcakes you need?

Have a good night!

Mrs. T