How to calculate the number of pieces in the border of a puzzle? Is there any way to calculate how many border-pieces a puzzle has, without knowing its width-height ratio? I guess it's not even possible, but I am trying to be sure about it.
Thanks for your help!
BTW you might want to know that the puzzle has 3000 pieces.

Admitting it's a regular grid of 3000 pieces, no more, no less, there aren't that many possibilities for the size of the borders, as they must be a divisor of 3000.
However, even if you don't know the ratio, it's usually safe to assume it's between 1:1 and 2:1, as most puzzles are nice rectangles (using a very-non-mathematical notion of nice, by which I mean, most pictures, paintings, sheets of paper, screens, etc...).
This leaves us with the following possibilities:


*

*50x60 -> 2x48 + 2x58 = 212 border pieces and 4 corners

*40x75 -> 2x38 + 2x74 = 224 border pieces and 4 corners

*30x100 is already far from a 2:1 ratio but would yield 2x28 + 2x98 = 252 border pieces and 4 corners.

