Estimating Sums & Differences

Front

What is estimating sums?

Back

Estimating sums involves rounding numbers to make them easier to add, allowing for a quick approximation of the total.

Front

How do you round 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

Estimate the sum: 123 + 456 (rounded to the nearest hundred).

Back

600

Front

What is estimating differences?

Back

Estimating differences involves rounding numbers to make them easier to subtract, allowing for a quick approximation of the result.

Front

How do you round to the nearest ten thousand?

Back

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

Front

Estimate the difference: 47,623 - 12,385 (rounded to the nearest ten thousand).

Back

40,000

Front

How do you round 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

Estimate the difference: 642 - 137 (rounded to the nearest hundred).

Back

500

Front

What is the purpose of estimating in math?

Back

Estimating helps to quickly assess the reasonableness of an answer without calculating the exact value.

Front

How can you estimate how many more one group has than another?

Back

Estimate the sizes of both groups and subtract the smaller estimate from the larger one.