6th Grade Math Textbook, Progress

Multiply with Decimals

2-4

Mariko exchanged American dollars for British pounds.

If she had $48, and the exchange rate was 0.68 pounds

for each dollar, how many pounds did she receive?

To find the number of pounds, n, multiply: 48
0.68n.

First estimate by rounding: 48
0.68.

50 
 0.7 35

Then multiply.

To multiply a decimal by a whole number or

another decimal:


Multiply as you would with whole numbers.


Count the number of decimal places in both factors.


Mark off the same numberof decimal places in the product.

Multiply as with Write the decimal point

whole numbers. in the product.

0.6 8 
 0 .6 8


0.4 8 
 0 .4 8


5 4 4 
 5 .4 4

2 7 2 2 7. 2

3 2 6 4 3 2.6 4

Mariko received 32.64 pounds.

Study these examples.

 0 .3 2 9


 0. 0 0 .0 2

0 .0 06 5 8

2 decimal places

3 decimal places

2 decimal places

5 decimal places

Write 2 zeros.

$ 7 2.2 5


 0 .7 5

3 6 1 2 5

 5 0 5 7 5

$ 5 4.1 8 7 5

2 decimal places

2 decimal places

4 decimal places

$54.1875 rounded to the nearest cent is $54.19.

Think

32.64 is close to the estimate of 35.

2.0

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