Estimating Sums & Differences

Front

What is estimating in math?

Back

Estimating is finding a number that is close enough to the right answer, often by rounding numbers.

Front

What does it mean to round to the nearest hundred?

Back

Rounding to the nearest hundred means adjusting a number to the closest multiple of 100.

Front

How do you estimate the sum of 459 and 101 by rounding to the nearest hundred?

Back

Round 459 to 500 and 101 to 100. The estimated sum is 500 + 100 = 600.

Front

What is the nearest ten to 37?

Back

The nearest ten to 37 is 40.

Front

How do you estimate the sum of 37 + 99 by rounding to the nearest ten?

Back

Round 37 to 40 and 99 to 100. The estimated sum is 40 + 100 = 140.

Front

What is the best estimate for the total number of items if Tracy ordered 325 pet toys and 165 bags of dog food?

Back

Round 325 to 300 and 165 to 200. The estimated total is 300 + 200 = 500.

Front

What does it mean to estimate the difference?

Back

Estimating the difference means finding a close value for how much one number is greater or less than another.

Front

How do you estimate how many more fourth graders went on a field trip than fifth graders?

Back

Round 237 to 200 and 346 to 300. The estimated difference is 300 - 200 = 100.

Front

What is the nearest ten to 42?

Back

The nearest ten to 42 is 40.

Front

How do you estimate the sum of 42 + 59 by rounding to the nearest ten?

Back

Round 42 to 40 and 59 to 60. The estimated sum is 40 + 60 = 100.