digit sum

Given an integer m consisting of k digits d1,,dk in base b, let


then j is the digit sum of m. Iterating this operation on the digits of j until j<b gives the digital root or repeated digit sum of m. The digit sum and digital root of a number are the same only if the additive persistence of the digital root is 1.

Title digit sum
Canonical name DigitSum
Date of creation 2013-03-22 16:22:53
Last modified on 2013-03-22 16:22:53
Owner PrimeFan (13766)
Last modified by PrimeFan (13766)
Numerical id 5
Author PrimeFan (13766)
Entry type Definition
Classification msc 11A63