🔢 MathGrade 3Lesson 3
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Round Numbers to the Nearest 10 and 100

How to use: Download the PDF to print the worksheet. Then use this page to repeat activities and check answers.

Learning Objectives

  • 1Round a 2-digit number to the nearest 10 on a number line
  • 2Round a 3-digit number to the nearest 100 on a number line
  • 3Explain why a number rounds up or down based on the digit in the rounding place
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Mini Lesson

Rounding means finding the nearest 10 or 100 that a number is closest to. It helps us estimate quickly and work with simpler numbers. We use a number line to see exactly which "round" number a value is closest to.

The Rounding Rule

  • Look at the digit to the right of the place you are rounding to.
  • If that digit is less than 5, round down — keep the rounding-place digit the same.
  • If that digit is 5 or more, round up — increase the rounding-place digit by 1.
  • Replace all digits to the right of the rounding place with zeros.

Rounding to the Nearest 10

  • Look at the ones digit. If it is less than 5, round down: 23 → 20.
  • If the ones digit is 5 or more, round up: 47 → 50.
  • On a number line, 47 is between 40 and 50 and is closer to 50.

Rounding to the Nearest 100

  • Look at the tens digit. If it is less than 5, round down: 340 → 300.
  • If the tens digit is 5 or more, round up: 180 → 200.
  • A number exactly at the midpoint (e.g. 450) rounds up by convention.
Round 47 to the nearest 10A number line from 40 to 50 with 47 marked. An arrow shows 47 rounding up to 50 because the ones digit 7 is 5 or more.Round to the Nearest 104045504747 rounds UP to 50ones digit 7 ≥ 5 → round up
The Rounding RuleTwo panels showing the rounding rule. Left panel: ones digit less than 5 means round down, example 23 to 20. Right panel: ones digit 5 or more means round up, example 47 to 50.The Rounding Ruledigit < 5Round DOWN23 → 20digit ≥ 5Round UP47 → 5083 → 80 (3 < 5)65 → 70 (5 ≥ 5)Same rule works for hundreds too!
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To round to the nearest 10: look at the ones digit. To round to the nearest 100: look at the tens digit.

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Guided Practice

Tracing Pad

Tip: Say each number aloud as you round it.

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Exercises

Mark the rounded value on the number line for each problem.

Round 47 to the nearest 10. Tap the correct value.

40
45
50

Round 23 to the nearest 10.

20
25
30

Round 65 to the nearest 10.

60
65
70

Round 180 to the nearest 100.

100
150
200

Round 340 to the nearest 100.

300
350
400

Round 450 to the nearest 100.

400
450
500

Pick the best answer.

Round 38 to the nearest 10.

Round 75 to the nearest 10.

Round 250 to the nearest 100.

Round 420 to the nearest 100.

Round 82 to the nearest 10.

Round 16 to the nearest 10.

Round 550 to the nearest 100.

Round 93 to the nearest 10.

When the ones digit is less than 5, you round ___.

Round 760 to the nearest 100.

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Assessment

← Lesson 2Lesson 4 →