AHi all I'm new to this site and new ish to baking.

I've been asked to do a 5 & 0 cske to feed 70 - 80 people, I have never done a number cake and haven't a clue what size cake to use and how big the numbers would need to be to feed that many people so thought I'd as you experts :)

Consider the average cake slice is 1 1/2" x 2" x 4" tall (from the board to the top of the cake), you'll need 3" square per guest (surface area of the cake), assuming your cake is 4" tall.

That's all too much math for me at the moment....

Help...anyone!?!

Approximately 30 each.  I get on to google and enlarge the No. 5 cake tin, height to be approx. 14" (I believe that's the height of the pan, place some baking paper over my computer screen and draw over, to make a template. assuming the size of each piece is 1x2x height I draw it on the paper and get my number of pieces.  hope I haven't confused you.

I think I would do this: 

- Plan that each number should give you similar amounts (35-40 servings)

- Make a round cake for the "0" that's just slightly larger than that number (you will lose some servings in the middle and/or shaving the edges), so I'd use a 12" pan, which is normally 40-50 servings.

- Make another cake for the "5" so that the two are similar in scale (you could use another 12" round, a quarter sheet pan, which is 12" in length, or a 9x13", if that is what you have handy)

- Get carving! I would carve the shapes as wide as artistically appropriate, in order to not waste cake. You could print out a 5 and an 0 in a bold font if that helps you think of it.

This is assuming that you are making 2-3 layers of cake, plus filling, to achieve a finished height of 3-4". 

PS - this is approximate because I don't know your situation. Is it a paying customer and you absolutely have to cover your butt in serving numbers? Or is it friend's party, where there are other desserts? Is it a bunch of big eaters, or all women who will refuse cake or ask for a "sliver"?

If you can carve the center of "0" cleanly and get it out in one piece, you can save and frost for an extra few servings.