3 Digit Addition With Regrouping For Kids
3 digit addition with regrouping becomes much easier when you line up each number by place value and work from right to left. The key idea is simple: add the ones first, then the tens, then the hundreds. When a column makes 10 or more, you regroup by carrying to the next place. Clear setup and careful carrying help you find the correct sum every time.

source: Cazoom Maths
Set Up the Columns

source: Superstar Worksheets
Start by writing the numbers vertically so ones are under ones, tens under tens, and hundreds under hundreds. If the digits are not lined up, the answer can be wrong even before you begin adding. For example, in 348 + 276, write 8 under 6, 4 under 7, and 3 under 2. Then add each column from the right side first. This keeps place value organized and makes regrouping much easier to see.

source: Lucky Little Learners

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Regroup as You Add
Now add the ones column. If the total is 10 or more, write only the ones digit and carry the tens digit to the next column. For 348 + 276, 8 + 6 = 14, so write 4 in the ones place and carry 1 to the tens column. Then add the tens: 4 + 7 + 1 = 12, so write 2 and carry 1 to the hundreds column. Finally, add the hundreds: 3 + 2 + 1 = 6. The sum is 624.

source: Math Salamanders
A good quick check is to estimate first. Round 348 to 300 and 276 to 300, so the answer should be close to 600. Since 624 is near 600, it makes sense. You can also re-add by columns or check that each carried number was included once. This extra step helps catch mistakes like forgetting the carried digit or writing it in the wrong place.

source: K12 Math Worksheets
When practicing, focus on neat setup and one column at a time. Read the problem carefully, align the digits, and keep your carries small and visible above the next column. If a column does not add to 10 or more, simply write the total in that place and move on. With a little repetition, 3 digit addition with regrouping becomes a steady routine rather than a tricky step.



