It depends how big you want the slices.
You should order for only 90% of your guests. Some people will not eat the cake. So again, only order for 90% - in your case that means 12 people or one cake box mix - or one 9 inch round/square cake.
Layer Cake - novel - has 240 pages.
5-7 cups, generally chocolate cake mixes yield more and white mixes yield less
Depends on how big you cut the pieces. If you cut 2x2 inch pieces, a 12x18 cake will yield 54 servings.
There are 11 cups of batter in an 11x15 pan for a 2 inch layer. I would guess for an 11x13, maybe 10 cups?
that depends on how many slices you want.
about 1 and a half
4 boxes for a single pan
144 1-inch squares. 36 2-inch squares.
It depends what kind of cake it is. Usually, the nutrition facts will give you the answer.
144 1-inch squares. 36 2-inch squares.
for an 14 in round cake pan, you only need 1 box