In the diagram below (click on the image to get a larger version) you see two figures made up from the same pieces. In the upper figure the colored pieces are arranged so that the area of the figure is (13 x 5) ÷ 2 = 32.5 tiles. In the lower figure, the same colored pieces have been rearranged so that the area of the figure is (13 x 5) ÷ 2 - 1 = 31.5 tiles (the -1 is for the missing tile above the number 8.)
This is not an optical illusion; the grid lines are there to help demonstrate that all the squares are uniform. Feel free to print out a copy of the picture, cut out the colored pieces in one of the figures and lay them out on top of the other figure to prove that they are indeed the same size.
How can it be possible to disect a polygon, rearrange the order of the pieces and end up with less (or more) space than was used before?
