I just got asket to do a 3/4 sheet cake and I've never heard of that before. Any ideas??

I googled it and the size that came up a lot for 3/4 sheet cakes was 12"x24" but the number of servings was all over the place.

Ok..I know my math skills aren't working today, but how do I get a 12x24?

Two 12 x 12 square cakes put next to each other will give you a 12 x 24!

i did 3/4 sheet cakes all the time at the bakery... it's just 3 9x13 cakes laid side by side (the 13" side that is) on a full sheet board which is the biggest you can buy. make sure you put x-tra boards under it, they are alot heavier than you expect them to be especially with icing and all. we told people that they served about 60-75 people depending on how big you cut the pieces. hope i could help alittle! happy baking