Digit sum calculator

How to use this calculator

Edit DigitSum(12345); the decimal digit sum is 15. An optional second argument selects the base.

Tap the math below to edit it and see the result. Once a result is ready, press Tab on a hardware keyboard to accept it. Outside a matrix, Return completes the line; the phone math keyboard has the same Return action.

Try it here

Interactive tools require JavaScript. You can read the guide and example without it.

What to know

This is a digit sum, not repeated reduction to a digital root.

Mathlean combines visual mathematical input with computation and canvas tools. Results depend on the expression and available engine support; check important answers independently.