MathDB
Sum of digits equation

Source: Cono Sur Olympiad 2016, problem 4

August 28, 2017
number theorycono sur

Problem Statement

Let S(n)S(n) be the sum of the digits of the positive integer nn. Find all nn such that S(n)(S(n)−1)=n−1S(n)(S(n)-1)=n-1.
Back to ProblemsView on AoPS