Multiplication of Fractions

Copyright © 2000 by Monica Yuskaitis https://www.flocabulary.com/unit/multiply-fractions/

Why would I need to multiply a fraction by a another fraction?

You and your friends ate ½ of the 8 cookies that were in the jar You and your friends ate ½ of the 8 cookies that were in the jar. How many cookies did you eat? 4 1 2 of 8 =

You won 1 4 of the 20 remaining cards during a card game You won 1 4 of the 20 remaining cards during a card game. How many did you win? 5 1 4 of 20 =

Let’s try some trickier ones!! Today your family ate 1 3 of 1 2 of the leftover birthday cake from your 12th birthday. How much of the original cake did your family eat today? 1 6 1 3 of 1 2 =

Challenge!!!! Andy already read 1 2 of his novel. Today he read 1 12 of the remaining half of the book. How much of the book has he read in total? 1 24 1 12 of 1 2 = 1st Step: 13 24 12 24 + 1 24 = 2nd Step:

1 2 of 3 4 = 3 8 1 4 1 4 1 4 1 4 1 8 1 8 1 8

How to Find a Fraction of a Fraction The first thing to remember is that the word “of” means to multiply. of x =

Multiplying Fractions 1 2 4 4 2 x ÷ of = = 2 9 18 2 9 ÷ Step 1: If necessary, change the “of” to a multiplication sign. Step 2 – Multiply your numerators. Step 3 – Multiply your denominators. Step 4 – Simplify your answer. In this case we reduce.

Multiply and Simplify 1 9 9 3 3 of ÷ x = = 6 5 30 3 10 ÷

Multiply and Simplify 8 3 24 12 2 of x ÷ = = 9 4 36 12 3 ÷

Multiply and Simplify 7 4 28 4 of x 4 = = 2 3 6 6 2 4 = 3

Multiply and Simplify 3 3 9 27 of x = 3 = 4 2 8 8

Multiply and Simplify 7 8 56 2 of x 9 = = 3 2 6 6 1 = 9 3

Shortcut: You can simplify before multiplying by cross cancelling!!! 3 1.) Choose any one numerator and any one denominator that share a common factor and cross them out. 2.) Divide by the common factor and write down the new numerator and denominator. 3.) Multiply. *You may do this twice for each problem, if possible. 1 9 3 of x = 6 5 10 2

Cross Cancel 1 2 8 3 2 of x = 9 4 3 3 1

Cross Cancel 2 7 4 14 2 of x 4 = = 2 3 3 3 1

Cross Cancel and Multiply Super job! 1 4 3 3 of x = 2 4 2 1 1 1 = 2