Worksheet: Estimating Sums of Three-Digit Numbers

In this worksheet, we will practice estimating the sums of three-digit numbers.

Q1:

Look at how Farida rounded to estimate this sum.

Round the numbers in this sum to the nearest ten.

  • A
  • B
  • C
  • D

Calculate the estimate.

Q2:

Look at how Ramy estimated the sum.

Estimate the sum of 7 3 1 + 1 1 9 by rounding both numbers first to the nearest hundred.

Estimate the sum of 4 7 5 + 1 2 6 by rounding both numbers first to the nearest hundred.

Q3:

Look at this calculation.

Estimate the answer by rounding both numbers to the nearest hundred.

Estimate the answer by rounding both numbers to the nearest ten.

Find the exact answer.

Tip: Use the estimates to see if your answer is sensible.

Q4:

Look at how Dina estimated this sum.

Estimate the sum of by rounding both numbers first to the nearest ten.

Estimate the sum of by rounding both numbers first to the nearest ten.

Q5:

Look at how Adel rounded to estimate this sum.

Round the numbers in this sum to the nearest hundred.

  • A
  • B
  • C
  • D

Calculate the estimate.

Q6:

Sarah won 586 tickets at the fair. Her sister won 379.

Pick the best estimate for the total number of tickets that they won.

  • A 1 0 0 0
  • B800
  • C600
  • D900
  • E200

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