Math Calculators

Digit Sum Calculator

Calculate the sum of a number’s digits, plus its digital root found by repeated summing.

Digit sum —

Digital root —

About the Digit Sum Calculator

The digit sum adds together every digit in a number. Repeating that process on the result until a single digit remains produces the number's digital root.

Formula: Digit Sum = sum of all digits · Digital Root = repeat digit-summing until one digit remains

Digit sums are used in checksum algorithms, divisibility rules (a number is divisible by 9 exactly when its digit sum is), and recreational number theory.