No. 51.—Double Progressive Magic Square.
Figures 1, 2, 4, 8, 16, 32, 64, 128, 256. These numbers have been doubled from one upwards, and the puzzle is to place them in a square of three lines, so that the first multiplied by the second, and the product multiplied by the third each way, horizontally, perpendicularly, and diagonally, will produce the same amount. There are eight answers, all alike.