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Common Core Math3rd GradeNumbers in Base Ten

3.NBT.1: Round to the Nearest 10 or 100

Also written as 3.NBT.A.1 and CCSS.MATH.CONTENT.3.NBT.A.1 · Cluster: Use place value understanding and properties of operations to perform multi-digit arithmetic.

Make Rounding Number LinesAll 25 3rd Grade Math Standards

The Official Wording

Use place value understanding to round whole numbers to the nearest 10 or 100.

Common Core State Standards, Grade 3, Number & Operations in Base Ten · Read it at the source · Checked October 14, 2026

What 3.NBT.1 Means in Plain English

Third graders round by asking which ten or hundred a number is closer to, not by reciting a rule. 347 sits between 340 and 350 and lands nearer 350. Between 300 and 400 it is nearer 300, so to the nearest hundred it rounds to 300.

Rounding is an estimating tool here, used to check sums within 1000 (3.NBT.2) and answers to two-step word problems (3.OA.8). In 4th grade students round multi-digit numbers to any place, like 48,617 to 49,000 (4.NBT.3).

3.NBT.1 I Can Statements

  • I can round a three-digit number to the nearest ten.
  • I can round a three-digit number to the nearest hundred.
  • I can use a number line to show which is closer.

3.NBT.1 Worked Example

One number rounded two ways, with the number line doing the deciding.

Problem

Round 268 to the nearest ten and to the nearest hundred.

Rounding 268 two ways
  1. Which two tens is 268 between?260 and 270
  2. Halfway between them is 265. 268 is past halfway, so it is closer to 270.268 → 270
  3. Now the hundreds. 268 is between 200 and 300, and halfway is 250.200 … 250 … 268 … 300
  4. 268 is past 250, so it is closer to 300.268 → 300
Answer268 rounds to 270 to the nearest ten and to 300 to the nearest hundred.

Check it: Count the distances: 268 is 2 from 270 and 8 from 260, and 32 from 300 and 68 from 200. The closer number wins both times.

Common Mistakes with 3.NBT.1

Rounding to the wrong place

347 to the nearest hundred written as 350

Try this: Have students name both neighbors first, 300 and 400, so the answer can only be one of those two numbers.

Rounding down by lowering the digit

263 rounded to the nearest ten as 250

Try this: Show 263 on a number line between 260 and 270. Rounding down keeps the tens digit, so the answer never drops below 260.

Rounding in a chain

348 to the nearest hundred: 348 → 350 → 400

Try this: Round from the original number every time. 348 is 48 away from 300 and 52 away from 400, so it rounds to 300.

Where 3.NBT.1 Fits

Comes Before2.NBT.1Know that the digits of a three-digit number are hundreds, tens and ones.2.MD.6Show whole numbers as equally spaced points on a number line.
Alongside3.NBT.2Add and subtract within 1000, with rounding as a first estimate.3.OA.8Check two-step word problem answers by rounding.
Comes Next4.NBT.3Round multi-digit whole numbers to any place.

Practice 3.NBT.1

Number Line GeneratorFree ToolLabeled lines from 200 to 300 in steps of 10, or 260 to 270 in ones. Students mark the number and the halfway point, then pick the closer end.Steps of 10Steps of 1Labeled ends
Make Number Lines
Math Worksheet GeneratorFree ToolRound-to-10 and round-to-100 items within 1000, with an answer key. Include a few numbers that end in 5 and 50.RoundingWithin 1000Answer key
Make a Worksheet

Quick Check

  1. Round 583 to the nearest ten.
  2. Round 583 to the nearest hundred.
  3. Round 745 to the nearest ten and to the nearest hundred.

3.NBT.1: Other Names

3.NBT.13.NBT.A.1CCSS.MATH.CONTENT.3.NBT.A.1

Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved. Official wording from the Common Core State Standards PDFs at corestandards.org, last checked October 14, 2026. The explanation, I can statements, example, mistakes and practice on this page are EMStudio’s own, written beside the official wording. They are not part of the standard.