Problem of the Week 1238
Change of Base
Define f from [0, 1] to [0, 1] by taking a real x, writing it in
For example, f(1/3) = f(0.010101...) = 1/99.
What is the integral of f from 0 to 1?
You may assume that f is Riemann integrable (this is so because there are countably many discontinuities).
Source: The problem is Problem 6 on the 2014 University of Illinois Math Contest. Heard from Keith Kearnes, Univ. of Colorado.