About

Long addition (or column addition) is the standard method for summing large numbers by aligning them vertically by their place value (ones, tens, hundreds). Mastering this technique is a cornerstone of elementary arithmetic, specifically the concept of "carrying" or "regrouping"-when the sum of a column exceeds 9, the tens digit transfers to the next column to the left.

This tool transforms the abstract process into a visual worksheet. Unlike standard calculators that just show the result, this application generates a grid that explicitly displays the carry values above the digits, helping students verify their manual calculations. It supports adding an unlimited number of rows, making it suitable for complex accounting-style sums or creating practice problems for teaching.

Formulas

For a column i with digits d₁, d₂, ..., d_n:

Sum_i = n∑k=1 d_k,i + Carry_i-1

If Sum_i ≥ 10, then:

ResultDigit_i = Sum_i mod 10
Carry_i = floor(Sum_i ÷ 10)

Reference Data

Term A	Term B	Sum	Logic
5	3	8	No Carry
5	5	10	Write 0, Carry 1
8	4	12	Write 2, Carry 1
9	9	18	Write 8, Carry 1
50	50	100	Two columns carry
99	1	100	Cascade Carry

Frequently Asked Questions

Carrying (or regrouping) happens when the sum of digits in a single column is 10 or greater. The "ones" part of the number stays in that column, while the "tens" part moves to the next column to the left.

Yes. This tool is designed to handle a stack of numbers. You can input as many lines of numbers as you wish, and the tool will calculate the total sum, managing carries that may exceed 1 (e.g., if a column adds up to 24, the carry is 2).

The calculator is limited only by the width of your screen. It handles "Big Integers", meaning you can add numbers with hundreds of digits without errors.

Yes. The layout is optimized to look like a school worksheet. You can use your browser's Print function to print the grid for homework or grading.