A single digit resulting from adding the digits of a number or adding the digits of the resulting number until a single digit is achieved.
For example, the digital root of 12345 can be found as follows:
- 1+ 2 + 3 + 4 + 5 = 15;
- since the number 15 has more than one digit, we do it again: 1 + 5 = 6;
- hence, the digital root of 12345 is 6.
The digital roots can provide valuable independent checks for complicated calculations.