|
Rounding
is one way to estimate
sums and difference.
Round 53,
55, and 58 to
the nearest ten. Estimate the sum.
| 50 |
51 |
52 |
53 |
54 |
55 |
56 |
57 |
58 |
59 |
60 |
|
|
 |
|
50
|
53
is between 50 and 60. It is closer to 50 Round
down to 50. |
55
is halfway
between 50 and 60. Round up to
60. |
58
is between 50 and
60. It is closer to 60. Round up
to 60. |
60 |
|
|
|
53
50
55
60
+58
+ 60
?
170 |
|
|
|
| To
round numbers: |
- Find the place you
are rounding to.
|
- Look at the digit
to its right.
|
| If
the digit to the right of the place one is rounding to is less
than 5, round down; if it is 5 or greater, round up. |
|
|
|
Example: Round
to the nearest ten.
|
Estimate
the sum. |
Estimate
the difference. |
|
36
+44
?
|
40
+40
80
|
52
-25
?
|
50
-30
20
|
|
Example: Round to the nearest hundred.
|
Estimate
the sum. |
Estimate
the difference. |
|
256
+444
?
|
300
+400
700
|
536
-154
?
|
500
-200
300
|
|
|
|
Remember to round
both numbers to the same place value when estimating a sum
or a difference. When a number is
halfway between two numbers, round
to the greater number. |
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2001-2011
Oswego City School District
Elementary Test Prep
Center
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| 
