Fraction Multiplication
6 x 1/5 = ____
6 x 1/5 = 6/5 or 1 1/5
5 ÷ 1/2 = ___
5 ÷ 1/2 = 10
In Ms. Erica's class, 3/5 of the 25 students are boys. How many boys are there in Ms. Erica's class?
There are 15 boys in Ms. Erica's class.
Ms. Grace is a little confused about multiplying fractions. She sees a problem that is missing the second factor. 1/3 x ___ = ___
What can you tell Ms. Grace about this problem:
a. the answer will be less than 1
b. the answer will be less than the missing factor
c. the answer will be a fraction
d. the answer will be greater than the missing factor
Explain your answer!
The answer will be less than the missing factor.
If you multiply a number by 1/3, it's the same as finding one-third of the number, so the answer has to be less than the starting number.
1/4 x 1/2 = ___
1/4 x 1/2 = 1/8
1/3 ÷ 4 = ___
1/3 ÷ 4 = 1/12
At Centennial, 2/3 of the school playground is covered with grass, and 3/5 of the grassy area is a baseball field. How much of the school playground is taken up by the baseball field?
Make a labeled sketch to model this problem and use the sketch to solve.
Write an equation to match, and write a complete sentence to show the answer.
Equation:2/3 x 3/5 = 6/15 or 2/5
Answer: The field takes up 6/15 of the playground.
Yesenia says that 6 ÷ 1/2 means the same thing as 1/2 of 6, so the answer is 3. Do you agree with her? Why or why not? Use numbers, labeled sketches, or words to explain your thinking.
Yesenia is not correct. There are 2 halves in one whole, so there are 6 x 2 or 12 halves in 6 wholes. 6 ÷ 1/2 = 12.
8 x 2/3 = ___
1/3 x 1/4 = ___
8 x 2/3 =16/3 or 5 1/3
1/3 x 1/4 = 1/12
7 ÷ 1/5 = ___
1/6 ÷ 8 = ___
7 ÷ 1/5 = 35
1/6 ÷ 8 = 1/48
There is 1/2 of a pan of brownies left. Four children are going to share it equally. What fraction of the whole pan of brownies will each child get?
Write an expression to represent this problem.
Use numbers AND labeled sketches to solve the problem.
Expression: 1/2 of 4 = _____
Answer: Each child will get 1/8 of the whole pan of brownies.
Isaac watched his friend multiply 3/4 x 5/6. His friend got an answer larger than 5/6. Isaac think that the answer is not correct. Do you agree? Why or why not?
Isaac is correct. 15/24 is less than 5/6. When you multiply a fraction by a fraction the product is always less than the second factor since you are breaking the first fraction into smaller fractions.
40 x 5/8 = ___
40 x 5/8 = 200/8 or 25
12 ÷ 1/5 = ___
1/9 ÷ 7 = ___
12 ÷ 1/5 = 60
1/9 ÷ 7 = 1/63
Ms. Lauren made cupcakes and now she wants to frost them. She has 4 cups of frosting. It takes 1/3 of a cup of frosting for each cupcake. How many cupcakes can she frost?
Write an expression to represent this problem.
Use numbers AND labeled sketches to solve the problem.
Expression: 4 ÷ 1/3 = ___
Answer: Ms. Lauren can frost 12 cupcakes.
Lucus says that dividing 1/2 by 3 is the same as multiplying 1/2 by 1/3. Do you agree with him? Why or why not? Use numbers, labeled models, or words to explain your thinking.
Lucus is correct. 1/2 ÷ 3 = 1/6 and 1/2 x 1/3 = 1/6
3/7 x 5/9 = ___
73 x 4/8 = ___
3/7 x 5/9 = 15/63
73 x 4/8 = 292/8
15 ÷ 1/6 = ___
1/12 ÷ 7 = ___
15 ÷ 1/6 = 90
1/12 ÷ 7 = 1/84
It takes 1/8 of a cup of sugar to make a batch of waffles. Ms. Erin has 6 cups of sugar. How many batches of waffles can she make?
Write an expression to represent this problem.
Use numbers AND labeled sketches to solve the problem.
Expression: 6 ÷ 1/8 = ___
Answer: Ms. Erin can make 48 batches of waffles!
PS Ms. Lauren is really happy about this.