The combinations tower, a theoretical-probability artifact, is the distributed binomial sample space of a stochastic device from the X-Block family, such as a 4-Block, a 2-by-2 grid in which each square can be either of two colors. The 16 unique configurations of the 4-Block are arranged in the tower according to the number of white (green) cells in them, resulting in a 1-4-6-4-1 formation (the corresponding binomial coefficients). This is the anticipated shape of the outcome distribution from experiments with the marble box containing equal numbers of marbles of each color.
