Today we will compute Today we will compute simple multiplication of simple multiplication of
fraction and mixed numbersfraction and mixed numbers
Compute=Work out
Mixed number=fractions with whole numbers
Copyright © 2000 by Monica Yuskaitis
ComputeCompute
Compute is when you work out a problem. For example, a math problem might ask you to compute the product of 5 and 6. You would then write:
5x6=30.
Copyright © 2000 by Monica Yuskaitis
Mixed NumbersMixed Numbers
Mixed numbers are fractions that also have whole numbers. For example:
1 ½
2 ¼
3 ¾
Copyright © 2000 by Monica Yuskaitis
Times You Would Multiply a Times You Would Multiply a Mixed Number Times a FractionMixed Number Times a Fraction
In a car race, the track is 2 ¼ miles long. If the car breaks down ½ way through the
course, how far did you go? 1/2 of 2 1/4 or 1/2 x 2 1/4
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a FractionFraction
Step 1 - When you see a fraction problem you know when you read “of” in the problem you multiply.
ofx12
49
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a FractionFraction
Step 2 – Multiply your numerators straight across.
x 49
12 = 4
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a FractionFraction
Step 3 – Then multiply your denominators straight across.
x 49
12 = 4
18
Copyright © 2000 by Monica Yuskaitis
How to Find the Fraction of a How to Find the Fraction of a FractionFraction
Step 4 – Simplify your answer. In this case we reduce.
x 49
12 = 4
18÷÷
22= 2
9
Copyright © 2000 by Monica Yuskaitis
Multiply and SimplifyMultiply and Simplify
95
16
= 930 10
3ofx ÷÷
33
=
Copyright © 2000 by Monica Yuskaitis
Multiply and SimplifyMultiply and Simplify
34
89
= 2436 3
2ofx ÷÷1212
=
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a Mixed NumberMixed Number
The first thing to remember is “of” means multiply in mathematics.
of = x
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a Mixed NumberMixed Number
Step 1 - When you see a fraction problem you know when you read “of” in the problem you multiply.
ofx12
493
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a Mixed NumberMixed Number
Step 2 – Change the mixed number to an improper fraction.
x12
493x
+
27
27 + 4
319
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a Mixed NumberMixed Number
Step 3 – Multiply the numerators straight across.
x12
319
31=
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a Mixed NumberMixed Number
Step 4 – Multiply the denominators straight across.
x12
319
31=18
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction of a How to Find a Fraction of a Mixed NumberMixed Number
Step 5 – Simplify your answer. In this case change the improper fraction to a mixed number.
x12
319
31=18
18)311
1813
1318
Copyright © 2000 by Monica Yuskaitis
Multiply and SimplifyMultiply and Simplify
14
=x 47x
35
35 + 4
5 + 397
3928
28)391
1128
Copyright © 2000 by Monica Yuskaitis
Multiply and SimplifyMultiply and Simplify
47
=x 19x
27
27 + 1
3 + 289
11263
63)1121 49
63÷
÷77
= 79
Copyright © 2000 by Monica Yuskaitis
Multiply and SimplifyMultiply and Simplify
45
=x 34x
24
24 + 3
6 + 274
10820
20)1085 8
20÷
÷44 = 2
5
Copyright © 2000 by Monica Yuskaitis
It’s important to know how to It’s important to know how to multiply fractions and mixed multiply fractions and mixed
numbers because…numbers because…If you are ever helping your parents build a
house, you can help them cut wood.It will be on your CST’s!What are other reasons why it is important
to know how to multiply with fractions and mixed numbers?
Copyright © 2000 by Monica Yuskaitis
Steps to multiplying fractionsSteps to multiplying fractions1. Convert the whole
number to a fraction by putting a one under it.
2. Multiply the numerators!
3. Multiply the denominators!
4. If the numerator is greater than the denominator, divide the denominator into the numerator. The remainder is the fraction and the denominator stays the same.
x 45 =
32 5
8 1
32 5
Copyright © 2000 by Monica Yuskaitis
Steps to multiplying fractionsSteps to multiplying fractions
1. Multiply the numerators!
2. Multiply the denominators!
3. Reduce fractions using the greatest common factor!
x 45
14 = 4
20 4 20
÷÷
÷
4 4 =
1 5
Copyright © 2000 by Monica Yuskaitis
Steps to multiplying fractionsSteps to multiplying fractions
1. Multiply the numerators!
2. Multiply the denominators!
3. Reduce fractions using the greatest common factor!
x 57
35 = 15
35 15 35
÷÷
÷
5 5 =
3 7
Copyright © 2000 by Monica Yuskaitis
Let’s review what we learned!Let’s review what we learned!
What does compute mean?What are mixed numbers?What is ½ x ¼ =
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