Estimating Decimals
Finding the Sum
Finding the Difference
Fill in the Blank
Word Problems
100

Estimate the sum by rounding each number to the nearest whole.  


50.2 + 65.23

50 + 65 = 115

100

13.45 + 8.21

21.66

100

34.8 - 17.2

17.6

100

34.09 + _____ = 89.65

55.56

100

Carlos bought a paperback book for $9.27 and a hardcover book for $25.55.  If he paid with 2 twenty-dollar bills, how much change did he receive?

He received $5.18 in change.

200

Estimate the sum by rounding to the nearest whole.

9.81 + 14.332

10 + 14 = 24

200

3.3 + 5.9

9.2

200

213.8 - 75.95

137.85

200

 _____ - 53.76 = 13.76

67.52

200

Stephanie likes to ride her bike.  On the first day, she rode 14.96 miles.  On the second day, she rode 12.09 miles, and on the third day, she rode 22.87 miles.  

- What is the combined distance for the 3 days?

-  How much farther did she bike the third day than the second day?

- The combined distance she rode is 49.92 miles

- The difference in miles from day 3 to day 2 is 10.78 miles.

300

Estimate the difference by rounding to the nearest tenth.

39.36 - 18.73 

39.4 - 18.7 = 20.7

300

387 + 22.16

409.16

300

227 - 98.02

128.98

300

45.6 + ______ = 78.987

33.387

300

Martin has a rectangular yard.  His yard is 13.09 meters long and 4.89 meters wide.  

- Round the length and width to the nearest whole number.  Then find the estimated PERIMETER.  

Length- 13 meters

Width- 5 meters

Perimeter- 36 meters

400

Mrs. Lamba's classroom is 105.84 square yards, and Mr. Bach's classroom is 110.12 square yards.  What is the estimated total area of both classrooms is we round the decimals to the nearest tenth?

105.8 + 110.1 = 215.9 square yards.

400

4.8 + 9.8 + 7.3

21.9

400

What is the difference of 75 and 23.87

51.13

400

2.3 + ____ + 6.7 = 27.3

18.3

400

Martin has a rectangular yard.  His yard is 13.09 meters long and 4.89 meters wide.

-Round the length and width to the nearest TENTH.  Then estimate the perimeter of the yard.  

Length- 13.1 meters

Width- 4.9 meters

The estimated perimeter was 36 meters.

500

Estimate the sum of $33.98, $21.09, and $26.54 by rounding each decimal to the nearest tenth.

34.0 + 21.1 + 26.5 = 81.6

500

What is the sum of 113.46 and 32.34?

145.8

500

304 - 96.543

207.457

500

____ - 21.1 = 34.98

56.08

500

Kim's patio has an area of 22.87 meters.

 Bob's patio has an area of 20.99 square meters.

 Al's patio has an area of 31.09 square meters.

Lea's patio has an area of 14.76 square meters. 


Which two patios have the greatest difference in area?  What is the area?  Explain.


Al's patio and Lea's patio have a difference of 16.33 square meters.  In order to find out which two have the greatest area, you must take the patio with the greatest area and subtract it from the patio with the least area.   

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