6th Grade Math Textbook, Progress

Multiply Mixed Numbers

8-4

The weight of water is 62


1

2 
lb per cubic foot.

What is the weight of 2


4

5 
cubic feet of water?

To find the weight of 2


4

5 
cubic feet of water, w,

multiply: 2


4

5 
^62 

1

2 
lbw.

First estimate by rounding:

2 
^45 
 62 
^12 
 3  63  189

Then multiply.

To multiply with mixed numbers:


 Rename both factors as fractions

greater than or equal to one.

 Simplify using the GCF

where possible.

 Multiply the numerators. Then multiply

the denominators.

 Rename the product as a whole

or mixed number when needed.

The weight of 2


4

5 
cubic feet of water is 175 lb.

Study these examples.

^23 
 3 
^38 

^23 

^287 
 9  5 
^23 

^91 

^137 


1 9 3


^2

3


 3 
^3

8



^2

3



^2

8

(^7)

9
4

 2
^1
4

9  5
^2
3


^9
1


^1
3
(^7)

5
1
(^1)
 51
1 4 1
Estimate each product by rounding.

1. 7
   
   2
   3
   ^4
   

1

4 
 2.^9 

1

5 
^3 
 1

7

2 
 3.^8 ^9 

7

8 
 4.^7 

1

2 
^10

5. 
   
   5
   6
   ^32
   

4

7 
 6.^75 
 1

1

0 


3

5 
 7.^12 

1

4 
^5 

1

4 
 8.^15 

7

8 
^1 

5

9 

lb 2 
^45 
 62 
^12 

^154 

^122 
^5

7 25

2 


4

5 
^62 

1

2 
lb

1

5

(^4)



12
2

^5
1 1
2
^45
 62
^12
lb
^71 
.^215.
2
^45
 62
^12
lb
^171
^5  175
Think
175 lb is close to the
estimate of 189 lb.
Think
Estimate:
9  6  54
Think
Estimate:
1  3  3
GCF of 14 and 2: 2
GCF of 5 and 125: 5
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