Reduce a number to a single digit by repeatedly summing its digits.
Last updated: June 2026 | By Patchworkr Team
Non-digit characters are removed before evaluation.
A digital root is the single-digit value you get after repeatedly summing a number’s digits.
For non-zero numbers, it matches the congruence formula 1 + ((n - 1) mod 9).
The example matches the default input value.
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