Sum Calculator
Add up a comma-separated list of numbers to find the total sum.
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How to use this tool
- Enter numbers (comma-separated) in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your sum and the full breakdown beneath it.
Enter numbers separated by commas to find their sum.
Formula
Sum = x1 + x2 + … + xn
total = nums.reduce((a, b) => a + b, 0)
How it works
This calculator parses a comma-separated list of numbers and returns their total by summing all valid numeric entries using sequential addition (reduce). Non-numeric tokens are silently filtered out before summing. The result equals the arithmetic sum of all recognized numbers in the list; empty input returns 0.
Worked example
- Enter numbers: 1, 2, 3, 4, 5.
- Parse to [1, 2, 3, 4, 5] — all 5 values are valid.
- Sum = 1 + 2 + 3 + 4 + 5 = 15.
Sum = 15.
Common mistakes to avoid
- Including duplicate values accidentally when copying and pasting a comma-separated list from a spreadsheet.
- Mixing number formats (e.g. 1,000 as a thousands-separated number vs 1 and 000 as two separate entries) causing parsing errors.
- Forgetting that negative numbers must be entered with a minus sign; omitting it adds instead of subtracts.
Key terms
- Sum
- The result of adding a set of numbers together.
- Addend
- Any individual number being added in a summation.
- Reduce
- A programming technique that combines list elements one by one using an operation (here, addition) to produce a single result.
- Accumulator
- The running total held during the reduce operation, starting at 0 and increasing with each addend.
Frequently asked questions
- How do you add a list of numbers?
- Enter the numbers separated by commas and click Calculate. The tool adds all values together.