Fraction Review
Multiplying Fractions
Repeated Addition
Remember: Multiplication is finding "groups OF" a number
For example, 3 x 5 is 3 "groups of" 5. 5 + 5 + 5 =15, so 3 x 5 = 15 This is also called repeated addition.
When multiplying fractions by whole numbers, we are simply finding groups of that fraction.
5 x 2/3 5 "groups of" 2/3 really means: 2/3 + 2/3 + 2/3 + 2/3 + 2 /3
Since we have a common denominator, we know that the denominator in our answer will be the same.
Steps 1) Have a common denominator
2) Add numerators (top numbers)
3) Convert to a mixed number and/or reduce if necessary
5 x 2/3 = 2/3 + 2/3 + 2/3 + 2/3 + 2/3 = 10/3 Convert to a mixed # 3 1/3
For example, 3 x 5 is 3 "groups of" 5. 5 + 5 + 5 =15, so 3 x 5 = 15 This is also called repeated addition.
When multiplying fractions by whole numbers, we are simply finding groups of that fraction.
5 x 2/3 5 "groups of" 2/3 really means: 2/3 + 2/3 + 2/3 + 2/3 + 2 /3
Since we have a common denominator, we know that the denominator in our answer will be the same.
Steps 1) Have a common denominator
2) Add numerators (top numbers)
3) Convert to a mixed number and/or reduce if necessary
5 x 2/3 = 2/3 + 2/3 + 2/3 + 2/3 + 2/3 = 10/3 Convert to a mixed # 3 1/3
Using Models to Multiply Proper Fractions and Mixed Numbers
Proper Fractions |
We can use an overlapping array model to multiply proper fractions. The double overlap reveals the product of the two fractions.
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Mixed Numbers |
We can use a standard array model to determine the product of 2 mixed numbers. |