If you put a uniform block at the edge of a table the center of the block

Question:

If you put a uniform block at the edge of a table the center of the block must be over the table for the block not to fall off.
(a) If you stack two identical blocks at the table edge, the center of the top block must be over the bottom block, and the center of gravity of the two blocks together must be over the table. In terms of the length L of each block, what is the maximum overhang possible (Fig. 11.54)?
(b) Repeat part (a) for three identical blocks and for four identical blocks.
(c) Is it possible to make a stack of blocks such that the uppermost block is not directly over the table at all? How many blocks would it take to do this? (Try this with your friends using copies of this book.)