MathDB
Tower of cubes

Source: 2006 AIME I -- Question 11

March 8, 2006
geometry3D geometryinductionmodular arithmeticratioAMCAIME

Problem Statement

A collection of 8 cubes consists of one cube with edge-length kk for each integer k,1k8.k,\thinspace 1 \le k \le 8. A tower is to be built using all 8 cubes according to the rules: \bullet Any cube may be the bottom cube in the tower. \bullet The cube immediately on top of a cube with edge-length kk must have edge-length at most k+2.k+2. Let TT be the number of different towers than can be constructed. What is the remainder when TT is divided by 1000?