Set up a chess board with all the pieces in their correct starting positions. Now remove all the Pawns. There are now four unthreatened squares on the board.

How many, and which pieces can you remove from the board so that the position and number of unthreatened squares remains unchanged?

Does a piece "threaten" the square it sits on? If it does, you can also remove either (but not both) of the queen-side rooks.

Both king-side rooks are needed, however, to threaten the squares from which you removed the king-side knights.

Besides this, Joe's solution is the best I came up with, as well.

Posted by TomM on 2005-01-02 14:32:47