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 Sophia 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 David 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 Mia 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 Anthony rounded to estimate this sum.

Round the numbers in this sum to the nearest hundred.

  • A
  • B
  • C
  • D

Calculate the estimate.

Q6:

Amelia 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:

Isabella 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?

  • A215682
  • B682+215
  • C682215

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.

Hint: 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

Q10:

Choose the number that is closest to 337+342, using rounding to the nearest tens.

Q11:

Jackson wanted to estimate the result of 256+372 using a number line. He rounded both numbers to the nearest hundred.

Use the number line to find 256 to the nearest hundred.

Use the number line to find 437 to the nearest hundred.

What is the estimate of the result of 456+372?

Q12:

Use <, >, or = to fill in the gap: 369+203414+357.

  • A>
  • B=
  • C<

Q13:

Which is bigger: five hundred and sixty three or 162+113?

  • Asame
  • Bfive hundred and sixty three
  • C162+113

Q14:

Use <, >, or = to fill in the gap: 468+331100+563.

  • A<
  • B>
  • C=

Q15:

Use <, >, or = to fill in the gap: 428+486382+138.

  • A>
  • B<
  • C=

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