Quilting Math

I am making a rainbow quilt for a baby out of "half square triangles" and I have never had so many issues with math before! I am going to have 360 2.5" squares and I am trying to figure out how wide and tall the quilt should be without any leftover pieces.

Dudes, I am good at math! Why can't I figure this out? Here are all the options (in number of squares):

1 X 360
2 x 180
3 x 120
5 x 72
6 x 60
8 x 45
9 x 40
10 x 36
12 x 30
15 x 24
18 x 20

The 18 x 20 is a 45" x 50" quilt. The 15 x 24 is 37.5" x 60". So which do you think would be nicer for a baby?


Also, how am going to lay out the 360 and keep them in order while I am sewing them together?