Q) A checkerboard of 13 rows and 17 columns has a number written in each square, beginning in the upper left corner, so that the first row is numbered 1, 2, . . . , 17, the second row 18, 19, . . . , 34, and so on down the board.
If the board is renumbered so that the left column, top to bottom, is 1, 2, . . . , 13, the second column 14, 15, . . . , 26, and so on across the board, some squares have the same number in both the ways. Find the sum of these numbers.
Solution