Digit Sum Calculator
The digit sum calculator helps you calculate the total sum of the digits in the given numbers.
Digit sum29
Digital root2reduced to a single digit
Digits4
Divisible by 3?No
Divisible by 9?No
Reducing to the root
| Pass | Sum |
|---|---|
| 1 | 9 + 8 + 7 + 5 = 29 |
| 2 | 2 + 9 = 11 |
| 3 | 1 + 1 = 2 |
The method
add the digits; repeat to reach the digital root
The digital root is n mod 9
Repeatedly summing digits lands on 1 + (n−1) mod 9 for any positive n. That is why the digit sum tests divisibility by 3 and 9, and it is the basis of "casting out nines" — an old way of checking arithmetic by hand.