Download Notes 39-46--Multiplying Fractions Page 1 of 2 Name

Name: ____________________________Date: ___________________________
Class: Developing College Math Skills
Objective: We will multiply fractions with fractions, whole numbers, and mixed numbers by
completing pages 39-46.
Multiplying Fractions
*The answer to a multiplication problem is called the product.
*When you multiply fractions, you are finding a fraction of a fraction.
*To multiply fractions, multiply the numerators together and multiply the denominators together.
*With 3 fractions, multiply the numerators of the first two fractions together. Then multiply that
answer by the third numerator.
Example: The owner of a ¾ acre of land plans to sell ½ of the land. How large is the parcel that
he plans to sell?
Find ½ of ¾
Step 1: Multiply the numerators. 1x3=3
Step 2: Multiply the denominators. 2x4=8
Answer: The size of the parcel of land is 3/8 acre
Cross Canceling when Multiplying Fractions
*Canceling is a shortcut in the multiplication of fractions. It’s just like reducing. It means
dividing a numerator and a denominator by a number that goes evenly into both before actually
multiplying.
Example 1: 10/21 x 14/25=
Step 1: Cancel 10 and 25 by 5.
10÷5=2 and 25÷5=5
Step 2: Cancel 14 and 21 by 7.
14÷7=2 and 21÷7=3. Cross out the 14 and the 21.
Step 3: Multiply across by the new numbers.
2x2=4 and 3x5=15
Example 2: 4/11 x 5/12 x 11/15
Notes 39-46--Multiplying Fractions
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Multiplying Fractions and Whole Numbers
*Any whole number can be written as a fraction with a denominator of 1.
Example: 9 x5/6
Step 1: Write 9 as a fraction. 9= 9/1
Step 2: Cancel 9 and 6 by 3
Step 3: Multiply across by the new numbers
Step 4: Change the improper fraction to a mixed number.
Multiplying Mixed Numbers
*To multiply with mixed numbers, change every mixed number to an improper fraction.
Example: 4 ½ x 5/6
Step 1: Change 4 ½ to an improper fraction
Step 2: Cancel 9 and 6 by 3
Step 3: Multiply across.
Step 4: Change the improper fraction to a mixed number.
Rounding and Estimating
*To estimate a multiplication problem with mixed numbers, round each mixed number to the
nearest whole number. Then use the whole numbers to multiply.
A. For a mixed number with a fraction of ½ or more, round to the next whole number.
Examples: 5 ¾ ______ 8 ½ ________ 2 5/9 ________
B. For a mixed number with a fraction less than ½, drop the fraction and use the whole
number.
Examples: 7 3/8 ______ 10 1/3 ________ 1 2/7 ________
Example: Estimate the answer to 5 ¾ x 2
Step 1: Round 5 ¾ to the nearest whole number
Step 2: Multiply the rounded numbers
Step 3: Find the exact answer
Applying Your Multiplication Skills
Example: Solve and write correct label next to each answer. Reduce each answer to lowest
terms.
1. Jack’s regular work week is 40 hours. One week he worked 4/5 of the time. How many
hours did he work that week?
Notes 39-46--Multiplying Fractions
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