Worksheet: Estimating Sums of Three-Digit Numbers: Rounding

In this worksheet, we will practice rounding to the nearest ten or hundred to estimate the value of sums up to 1000.

Q1:

Look at how Scarlett 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 James estimated the sum.

Estimate the sum of 731+119 by rounding both numbers first to the nearest hundred.

Estimate the sum of 475+126 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 Amelia estimated this sum.

Estimate the sum of 615+209 by rounding both numbers to the nearest ten.

Estimate the sum of 262+147 by rounding both numbers to the nearest ten.

Q5:

Look at how Noah rounded to estimate this sum.

Round the numbers in this sum to the nearest hundred.

  • A
  • B
  • C
  • D

Calculate the estimate.

Q6:

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

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

  • A800
  • B1,000
  • C200
  • D900
  • E600

Q7:

Elizabeth is going on vacation. She will travel 215 miles by train and 682 miles by plane.

Which calculation do you need to do to figure out how many miles she will travel altogether?

  • A 2 1 5 6 8 2
  • B 6 8 2 + 2 1 5
  • C 6 8 2 2 1 5

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.

Q8:

Class A and Class B were collecting money for charity.

Class A raised $217.

Class B raised $389.

Pick the best estimate for the total amount they raised.

  • A$400
  • B$700
  • C$500
  • D$200
  • E$600

How much did they actually raise?

Q9:

Choose the number that is closest to 110+368.

  • A600
  • B500
  • C400

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