Consider cubes of edge length 5 composed of 125 cubes
Source: German TST 5, P1, 2009
July 18, 2009
geometry3D geometryalgebra unsolvedalgebra
Problem Statement
Consider cubes of edge length 5 composed of 125 cubes of edge length 1 where each of the 125 cubes is either coloured black or white. A cube of edge length 5 is called "big", a cube od edge length is called "small". A posititve integer is called "representable" if there is a big cube with exactly small cubes where each row of five small cubes has an even number of black cubes whose centres lie on a line with distances (zero counts as even number).
(a) What is the smallest and biggest representable number?
(b) Construct 45 representable numbers.