Estimating Sum and Difference of Decimals

Which is the best estimate of 61.4 + 88.3?

• 100

• 140

• 150

• 200

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

428.1 + 186.5 + 210.62

Estimate the sum.

78.5 + 51.2

Estimate the difference.

968.8 - 161

In the equation 497.55 - 265.41 = 232.14, the number 232.14 is the _________________

• difference

• quotient

• compatible numbers

In the equation 8.9 + 55.2 = 64.10, the number 64.10 is the _________________

• difference

• sum

• product

Estimating is finding a value that is CLOSE or APPROXIMATE to the actual value, but it's not exact.

• True

• False

Choose a good pair of compatible numbers to make finding the sum of 223.4 + 148.9 easier to add mentally.

• 200 + 100

• 223 + 149

• 225 + 150

• They're already compatible.

Estimate the sum of 0.87 and 1.49 to the nearest tenth.

• 2.0

• 2.3

• 2.4

• 2.5

The best estimate of the sum of 3.78 and 5.2 to the nearest whole is

• 4.30

• 8

• 8.98

• 9