If a series of identical rectangular blocks is stacked out at their balancing points from the top down, the top block can stick out arbitrarily far. You can show with a simple center of mass calculation the total "stick-out" distance; that is, the horizontal distance from the back of the bottom block to the back of the top block is 1/2(1 + 1/2 + 1/3 + 1/4 + ...). This series grows without limit.

Many students are surprised to see the top block "sticking out in space", no part of it over the bottom block of the stack. The series above shows that this can happen with a stack of only 6 blocks. In practice at least 6 are needed, and several more to make to effect dramatic.