Last updated September 18, 2026 · Report an error
Long addition is the standard elementary-school method of adding multi-digit numbers column by column, carrying digits as needed. This tool shows the complete working for any two whole numbers, not just the final sum.
How it works
Digits are aligned by place value, and each column (starting from the rightmost, ones place) is added together with any carry from the previous column. If a column's total is 10 or more, a 1 is carried into the next column to the left.
- Enter first number.
- Enter second number.
- Click Calculate to see your results.
Examples
Adding two 4-digit numbers
4785 + 2936: adding column by column with carries gives 7721.
Who should use it
- Elementary school addition homework and practice.
- Verifying manual long-addition work.
Industry applications
- Education (elementary arithmetic)
Advantages
- Shows every column's working, including all carries, not just the final answer.
- Handles numbers of different lengths automatically.
Limitations
- Currently supports non-negative whole numbers only.
Common mistakes to avoid
- Forgetting to carry a digit when a column sums to 10 or more, which throws off every digit to the left.
Best practices
- Work strictly right to left, one column at a time, and write down any carry immediately before moving to the next column.
Tips
- If your manual answer differs from the tool's, compare column by column against the shown working to find exactly where a carry was missed.
Frequently asked questions
Aligning by place value (padding the shorter number with leading zeros) ensures each column being added actually represents the same place — ones with ones, tens with tens, and so on.
The ones digit of that column's sum is written down, and a 1 is carried into the next column to the left, exactly as taught in elementary long addition.