Add two whole numbers step by step and review the carries used in long addition.
Last updated: June 2026 | By Patchworkr Team
Long addition adds numbers from right to left, carrying tens into the next column whenever a column total reaches 10 or more.
1234 + 5678 = 6912
Does the tool accept decimals?
No. This visualizer is for whole numbers only, because the carry-by-place-value display assumes digits.
What if the numbers have different lengths?
That is fine. The shorter number is padded with zeros on the left during the addition process.
Why reject non-digits?
The tool is meant to show manual long addition, so malformed characters are rejected instead of being ignored.
Can I add very large numbers?
Yes. The math uses BigInt for the total so large whole numbers are supported safely.
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