Grade 3 math: Adding with regrouping within 1000

If your child is in Grade 3, the topic "Adding with regrouping within 1000" is one of the ideas where confidence is most often won or lost. Here is what it means in plain words, a worked example you can follow together, and a few simple ways to help at home.

What Grade 3 children learn

• Add ones, tens and hundreds, and trade 10 ones for 1 ten and 10 tens for 1 hundred
• Line the digits up by place value and add one place at a time
• Estimate first by rounding, to check that an answer makes sense

The key ideas

• Line up the digits so ones are under ones, tens under tens and hundreds under hundreds.
• Always start with the ones. If a place adds to 10 or more, trade 10 of them for 1 of the next place up.
• Add the traded ten or hundred in the next place. Do not forget it.
• Estimate first by rounding to the nearest 10 or 100. Your exact answer should be close to the estimate.

Quick examples

• 46 + 38 = 84: 6 + 8 = 14 ones is 1 ten and 4 ones, then 4 + 3 + 1 = 8 tens
• 275 + 148 = 423: ones 5 + 8 = 13, tens 7 + 4 + 1 = 12, hundreds 2 + 1 + 1 = 4
• 387 + 276 = 663: ones 7 + 6 = 13, tens 8 + 7 + 1 = 16, hundreds 3 + 2 + 1 = 6
• Estimate first: 298 + 405 is about 300 + 400 = 700, and the exact answer is 703

A worked example

How to help at home

• Ask your child to explain the first step of the worked example in their own words before you show them anything.
• Work through the "Try it yourself" question together, and talk about why the answer makes sense.
• Spend a few minutes a day on the free Tutorizer "Adding with regrouping" practice. Short and regular beats long and rare.
• If a step feels shaky, go back to the key ideas above and use objects, drawings or a number line.

Try it yourself

Want a challenge?

Next steps