Chapter 3 Decimals

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Chapter 3
Decimals
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
3.3
Adding and
Subtracting Decimals
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
Adding Decimals
The addition of decimals is related to the addition of fractions.
3 4
7
 
10 10 10
0.3  0.4  0.7
Adding Decimals
1.
2.
3.
Write the numbers to be added vertically and line up the
decimal points. Extra zeros may be added to the right of
the decimal points if needed.
Add all the digits with the same place value, starting
with the right column and moving to the left.
Place the decimal point of the sum in line with the
decimal points of the numbers added.
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
Adding Decimals
Example:
Add 718.97 + 496.5.
718.97
+ 496.5 0
1215.47
Write the numbers
vertically and line up the
decimal points.
Add zeros where necessary
for place holders.
This value is the same as 1215 47 .
100
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
Subtracting Decimals
The subtraction of decimals is related to the subtraction of
fractions.
4
3
1
5
10
2
10
3
10
5.4  2.3  3.1
Subtracting Decimals
1.
2.
3.
Write the numbers to be subtracted vertically and line
up the decimal points. Additional zeros may be added
to the right of the decimal point if not all numbers have
the same number of decimal place.
Subtract all the digits with the same place value, starting
with the right column and moving to the left. Borrow
when necessary.
Place the decimal point of the difference in line with the
decimal points of the two numbers being subtracted.
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
Subtracting Decimals
Example:
Subtract 243.967 – 84.2.
1 13 13
243.967
– 84.200
159.767
Write the numbers
vertically and line up the
decimal points
Add zeros where necessary
for place holders.
This value is the same as 159 767 .
1000
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
Subtracting Decimals
Example:
Subtract 8 – 1.623.
9 9
7 10 10 10
8. 000
– 1.623
6.377
Write the numbers
vertically and line up the
decimal points.
Add zeros where necessary
for place holders.
This value is the same as 6 377 .
1000
Copyright © 2012, 2009, 2005, 2002 Pearson Education, Inc.
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