1 box for a rather thin cake, but if you want a thick cake you will need 2 boxes.
It depends on the depth of the pan
It depends on how deep the pan is.
One can purchase cake boxes wholesale from many different locations. However one can purchase cake boxes from locations such as Sam's Club, Target, Kohls, Walmart and TheCustomBoxes.com.au.
4 boxes for a single pan
You can actually use one box alone but it will be thinner. you can actually use the amount of boxes of cake mix you want it will just get thicker.
For a 15x11-inch cake pan, you typically need about 2 to 3 boxes of cake mix, depending on the brand and recipe instructions. Most standard cake mix boxes yield about 4 to 5 cups of batter, and a pan of that size usually requires around 10 to 12 cups of batter. It's always best to check the specific box instructions for the best results.
The boxes I checked said one box would make a 13x9, so you will need about 1 1/2 boxes for a 12x18. Assuming the pan is deep enough you could use two boxes for a one layer 12x18 or you may want to make a two layer cake using 1 1/2 box per layer.
About 16 For a serving size of a 2"x2" piece Full Sheet: approx. 96 1/2 Sheet: approx. 49 1/4 Sheet: approx. 24 For a serving size of a 2"x3" piece Full Sheet: approx. 64 1/2 Sheet: approx. 32 1/4 Sheet: approx. 16
100,000,000,000,000,000,000 because of the crumbs!!
11 ft X 15 ft = 165 sq ft
I think 1 will do. 2 if you want a really big, puffy cake, but it might overflow. I always make cakes from scratch. They taste much better. I hate box cakes. People who use box recipes are lazy. Just get a cookbook. ;-)
A 12" x 18" cake pan will make 72 servings.