Estimating Sums & Differences

Front

What is estimating sums?

Back

Estimating sums involves rounding numbers to make them easier to add together quickly.

Front

What is estimating differences?

Back

Estimating differences involves rounding numbers to make them easier to subtract quickly.

Front

How do you round a number to the nearest hundred?

Back

Look at the tens digit: if it's 5 or more, round up; if it's 4 or less, round down.

Front

What is the estimated sum of 25,000 and 5,000?

Back

30,000.

Front

What is the estimated difference of 600 and 200?

Back

400.

Front

How do you round a number to the nearest thousand?

Back

Look at the hundreds digit: if it's 5 or more, round up; if it's 4 or less, round down.

Front

What is the estimated sum of 1,537 and 2,785 when rounded to the nearest hundred?

Back

4,300.

Front

What is the estimated difference of 642 and 137 when rounded to the nearest hundred?

Back

500.

Front

If Eastfield college has 1,537 students and Richland college has 2,785, how many fewer students does Eastfield have when rounded to the nearest hundred?

Back

1,300.

Front

What is the estimated difference between 237 fifth graders and 346 fourth graders?

Back

100 more.