Calculate with Long Addition
Your result will appear here.
Formula and variables
- dᵢ,ₖ
- the digit of addend i in place k
- cₖ
- the carry entering place k
- Sₖ
- the column total
Align numbers by place value, add each column from right to left, write the ones digit, and carry the remaining tens into the next column.
Domain note: Enter 2 to 8 non-negative whole numbers. Each addend may contain up to 30 digits.
How to use this calculator
- 1
Enter two to eight whole-number addends.
- 2
Align the values by their ones digits.
- 3
Add from the ones column toward the left, carrying when a column total is 10 or more.
- 4
Read the exact sum and review each recorded carry.
A complete example
Problem: Add 4,876, 2,958, and 639.
Substitution: 4876 + 2958 + 639
Result: 4876 + 2958 + 639 = 8473
Column carrying produces the exact whole-number sum 8,473.
Understand the result
The working panel lists columns from ones upward. A carry-out from one place becomes the carry-in for the place immediately to its left.
Common mistakes
- Failing to align the ones digits.
- Forgetting to add a carry into the next column.
- Writing the entire column total instead of its ones digit in the current place.
Frequently asked questions
How many numbers can I add?
You can add between two and eight whole numbers in one calculation.
How large can each addend be?
Each input can contain up to 30 digits, and the calculation uses exact whole-number arithmetic.
Why are decimals not accepted?
This tool teaches the whole-number long-addition algorithm. Use the regular Addition Calculator for decimal values.