By ToolzHive
About this tool
The addition calculator adds numbers exactly, however long they are. Unlike many calculators it uses exact decimal arithmetic, so 0.1 + 0.2 gives exactly 0.3 and very large numbers keep every digit. Add two numbers or a whole list, with decimals, negative numbers and thousands separators, and see the sum in standard and scientific notation.
How to use Addition Calculator
- Enter the first and second numbers. Commas and spaces are ignored.
- Add more numbers in the extra box, one per line or separated by commas.
- Read the sum, the full equation and the scientific notation.
Worked example
1,250.75 + 349.5 = 1,600.25. Paste a column of prices into the extra box to total a whole list at once.
Add decimal values
Align place values when adding by hand. For 12.50 + 3.75, add the hundredths, tenths and whole-number columns to get 16.25. Use the extra-number field for a longer list.
Why do some calculators show 0.1 + 0.2 = 0.30000000000000004?
Computers usually store decimals in binary floating point, which cannot represent 0.1 exactly. This calculator uses exact decimal arithmetic, so results are always precise.
How large can the numbers be?
There is no practical limit. Numbers with hundreds of digits are added exactly.
Can I add negative numbers?
Yes. Enter them with a minus sign, for example -45.5.
Put this guide into practice
- Addition Calculator — Add two or more numbers of any size exactly, including decimals and negatives.