Question 13
A square piece of graph paper of side length 30 mm contains 900 smallest squares each of side length 1 mm each. Its four rectangular corners, denoted by A, B, C, D in clockwise order, are cut away from the square piece of graph paper. The resultant graph paper, which has the shape of a cross, is shown in the figure below. Let N denote the total number of rectangles, excluding all the squares which are contained in the resultant graph paper. Determine the value of $N/10$.
