Enter two or more numbers into the numbers input field (one per line or separated by commas) and the Long Addition Calculator walks you through every column — ones, tens, hundreds, and beyond — showing exactly where carries happen. You get the total sum plus a full step-by-step breakdown of the long addition process, including any carrying at each place value.
Total Sum
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Numbers Added
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Step-by-Step Working
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A Long Addition Calculator is an online tool that adds two or more numbers using the traditional column addition method. It aligns each number by place value, then adds digit by digit from right to left, carrying any overflow to the next column — and shows every step so you can follow along.
Type your numbers into the input box, separated by commas or placed on separate lines, then click Calculate. The tool instantly displays the total sum and, if step-by-step mode is on, a full table showing what happens at each place value column including any carries.
Long addition is the classic written method for adding numbers. You stack the numbers vertically, aligning digits by place value (ones, tens, hundreds, etc.), then add each column from right to left. When a column sums to 10 or more, you write the ones digit of that sum and carry the tens digit to the next column.
Carrying happens when the digits in a column add up to 10 or more. You write the ones digit of the result in the answer row for that column, and carry the tens digit (always a 1 for normal addition) to the top of the next column to the left, where it gets added in with the other digits.
Yes. You can add as many positive whole numbers as you like. Just separate each number with a comma or put each on its own line. The calculator stacks all of them and adds every column together, carrying as needed.
This version is optimised for positive whole integers. For best results enter whole numbers without decimal points. If you need decimal addition, align the decimal points yourself and treat the digits as whole-number columns.
Long addition builds a deep understanding of place value and number structure. It is the foundation for more advanced arithmetic — including long multiplication and long division — and helps students check calculator results by hand.
A basic sum calculator gives you the total immediately with no working shown. Long addition shows every intermediate step — column alignment, individual digit sums, and carries — making it a learning tool, not just an answer machine.