It all depends on how you cut it. You cna do a simple 8-slice (Pizza-style). Cutting small, inch-wide or 1/2-inch-wide slices will give you far more pieces, too.
144 1-inch squares. 36 2-inch squares.
144 1-inch squares. 36 2-inch squares.
that depends on how many slices you want.
Normally 12-16 slices but it depends on the sise of the cake.
It depends how big you want the slices.
Assume both pizzas are cut into eight slices. 3 slices of the 12 inch pizza make an angle of3 pi/4 and area is 1/2 radius squared times angle where radius is 6 inch so area = 42.4 sq in 2 slices of the 16 inch pizza make an angle of pi/2 and area is 1/2 radius squared times angle where radius is 8 inch so area = 50.2 sq in so the two 16 inch slices give you more pizza
You slice a pizza six times right across the diameter to obtain twelve slices (wedges).
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.
as mANY
If you mean a slice of cake it is - tranche
Assuming you used the standard tube pan, anywhere from 8 to 12 slices depending upon whether it will be the stand alone dessert (8) or loaded with strawberries and cream for example (12)
It all depends on how thick the cake is. Try using a 10 inch or 12 inch pans that are 3 inches deep. Or you can do 8 inch, 10 inch, and 12 inch that are 2 inches deep and double layer each one and that would be enough. Where I live its hard to find 3 inch deep cake pans. See the Cakefairy link below for a listing of cake sizes per servings.