Addition Calculator
Add two or more numbers of any size exactly, including decimals and negatives.
5.0 (1 rating)Enter your values to see the result.
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Read the privacy policyHow this calculation works
Understand the method, inputs and limits behind your result.
- Formula
- Sum = a + b. Decimal values are aligned by decimal scale and added using integer arithmetic.
- Variables
- First number
- Second number
- More numbers (optional, one per line or comma separated)
- Units
- Use the units shown beside each input. Counts and ratios are dimensionless unless labeled otherwise.
- 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.
- Assumptions
- The result follows the selected options and supplied inputs. Displayed values may be rounded; check input precision before using the result.
- Source
- ToolzHive calculation guide and calculator implementation. External reference verification is pending.
- Last reviewed
- Review date not yet recorded.
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Clear instructions
Find steps, examples and limitations below.
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Open the tool in a supported web browser.
Free to use
No sign-up required. Tool-specific limits may apply.
How to use the Addition Calculator
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.
- 1 Enter the first and second numbers. Commas and spaces are ignored.
- 2 Add more numbers in the extra box, one per line or separated by commas.
- 3 Read the sum, the full equation and the scientific notation.
Example and practical tips
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.
Frequently asked questions
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.
Practical guides
-
How to Multiply Two- and Three-Digit Numbers
Work through multiplication using partial products, check two- and three-digit examples, and handle decimal places and negative signs.
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How to Use Addition Calculator
Add two or more numbers of any size exactly, including decimals and negative numbers, with no rounding errors. Free online addition calculator.
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