One to one.
Number of factor pairs = number of rectangles
The factor pairs are the length and width of the rectangles.
One to one.
As I understand it, the number of factor pairs is equal to the number of rectangles.
If you can compile a complete list of all different rectangular models with sides of integer length for a number then their lengths and breadths represent its factors.
(21,1)(7,3)
Too many to list.
1 and A
Too many to list here.
The factor pairs of 18 are (1 x 18), (2 x 9), (3 x 6)
8 and 1. 4 and 2.
1,24/2,12/3,8/4,6