There is a grid of 20 squares by 10 squares. How many different rectangles are possible?
(Note that square is a rectangle).

I got 44099

I made a table 20 x 20. (which I can't cut and paste here since it's too big.) And calculated all rectangle/square sizes. Those 1 square tall, could fit on each line 20 times. Those 2 squares tall 19 times, those 3 squares 18 times, etc. Each total (expept the perfect squares, would be multiplied by 2, to account for the vertical as well.... Does that make sense?

Posted by Cindy on 2004-01-22 16:27:32