 For example, when transforming the 7-square to the 8-square, we add 15 elements; these adjunctions are the 8s in the above figure.This gnomonic technique also provides a proof that the sum of the first "n" odd numbers is "n"2; the figure illustrates Applying the same technique to a multiplication table proves that each squared triangular number is a sum of cubes.In an acute isosceles triangle, it is possible to draw a similar but smaller triangle, one of whose sides is the base of the original triangle.