Estimating Decimal Sums and Differences

Roughly, approximately, and about are all clues for knowing when to round or estimate.

• True

• False

Which of the following is the best estimate for the equation:

70.2 - 59.7

• 25

• 10

• 3

• 19

Which of the following is the best estimate for the equation:

61.44 + 88.3

• 100

• 120

• 150

• 180

Estimate the sum by rounding each decimal to the nearest hundred.

428.1 + 186.5

• 500

• 600

• 700

• 800

Estimate the difference by rounding each decimal to the nearest ten.

17.52 - 12.03

• 12

• 11

• 15

• 10

Estimate the difference by rounding each decimal to the nearest hundred.

376.8 - 109.5

• 100

• 200

• 300

• 400

Which equation shows the correct way to estimate the sum of 12.5 and 5.4 by rounding to the nearest whole number?

• 12 + 5 = 17

• 13 + 5 = 18

• 12 + 6 = 18

• 13 + 6 = 19

Danielle has $17.95. Raj has $6.35. Which equation shows the best way to estimate the money they have together?

• $18.00 + $7.00

• $18.00 + $6.00

• $17.00 + $7.00

• $17.00 + $6.00

Fran bought sneakers for $54.26 and a shirt for $34.34. If Fran started with $100, about how much money does she have left?

• $35

• $20

• $5

• $80

Which is the best estimate?

4.97 + 13.02 (Round to the nearest whole)

• 14

• 16

• 18

• 19