Third Grade · Math · week 32

Rounding to the nearest 10 and 100

Round two- and three-digit numbers to the nearest 10 and 100 using place value.

Rounding gives a close, friendly number that is easier to work with. To round to the nearest 10, look at the ones digit: 5 or more rounds UP, 4 or less rounds DOWN. 47 rounds to 50; 43 rounds to 40.

For the nearest 100, look at the tens digit with the same rule. 380 rounds to 400; 340 rounds to 300. A number line helps you SEE which ten or hundred is closer.

📋 For the teacher
Teach it (10–15 min):
  • Use a number line to show which ten/hundred is closer before teaching the digit rule.
  • Name the digit to look at every time — place value is the key.
  • Practice why rounding is useful (quick estimates while shopping).
  • Keep the "5 rounds up" rule consistent.
Talk about it:
  • Which digit do you check to round to the nearest 10?
  • What is the rule for 5?
  • How does a number line help?

Mastery looks like: They round to the nearest 10 and 100 using the correct place-value digit.

Common stumbles: Checking the wrong digit; forgetting that 5 rounds up; rounding 68 to 60.

See it visually

Interactive, spoken-aloud tools that show this idea in motion.

Place ValueWatch ones, tens, hundreds, and thousands build big numbers.try →
Homework for this lessonType it, write it with a stylus, or print it for pencil & paper.open →
Records attendance + 15 min of Math for this learner.
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