Question

Match the sum or difference on the left to its best estimate on the right.

• A. 100
• B. 40
• C. 30
• D. 20

Answer 1

To find the estimate we round the numbers to their nearest tens.

$4140+\underset{–}{57}\to +\underset{–}{60}\underset{–}{98}\underset{–}{100}$

$\therefore$ The best estimate for $41+57$ is 98.

$7270-\underset{–}{34}\to -\underset{–}{30}\underset{–}{38}\underset{–}{40}$

$\therefore$ The best estimate for $72-34$ is 40.

$3740-\underset{–}{19}\to -\underset{–}{20}\underset{–}{18}\underset{–}{20}$

$\therefore$ The best estimate for $37-19$ is 20.

$5660-\underset{–}{29}\to -\underset{–}{30}\underset{–}{27}\underset{–}{30}$

$\therefore$ The best estimate for $56-29$ is 30.