Counting things must be done so with knowledge that there are multiple permutations you must consider.
Though Experiment
How many rectangles are there above?
You must count different sized rectangles too.
1x1: There are 5 rectangles 1x2: 4 rectangles 1x3: 3 rectangles 1x4: 2 rectangles 1x5: 1 rectangles 5+4+3+2+1 = 15
If you do the same with a 5x2 rectangle, you will find there are 45 rectangles. If you do the same with a 5x3 rectangle, there are 135 rectangles.
You may notice there is a pattern here: 15,45,135 it is a geometric sequence.