Digit Sum & Digital Root Calculator
Find a number’s digit sum.
Result
How to use
- Enter your values in the fields above.
- Press Calculate to see your result instantly.
- Use the Share button to copy a link to your result.
About this calculator
This calculator adds up all the digits of a number to get its digit sum, then repeats the process on the result until a single digit remains — the digital root. The digital root is always equal to the number's remainder when divided by 9 (with a special case for multiples of 9).
It's used to teach the “casting out nines” checksum trick for spotting arithmetic errors, in numerology, and by programmers writing simple validation or puzzle-solving code where a quick digit-based check is useful.
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