I'm looking to achieve gold shiny BC, not yellow-gold. Can you add lustre dust to get it sparkly?

The church just called and asked me to do a Confirmation cake for this weekend. It's to feed about 100; they have no idea how many will show. No more than 100 - they said they can cut small... BUT they want a sheet cake - my nemesis! I'm really stressing over this one. Would two 9x13's side by side work? That's 90 servings. How do you not get a line where they bump together?

Wait - something's not right!

I'm not the best at math... According to Wilton, a 12x18 double layer serves 72 party sized slices (1.5"x2"x4"). A 9x13 double layer serves 45. If you were to bump two 9x13 together, you'd have an 18x13, right? Which technically should serve 90.

So a 12x18 serves 72 and a 13x18 serves 90?? That's only 1" difference in width. 1" by 18" strip won't get you 18 extra servings at the party size of 1.5"x2".

Am I just not seeing it? Told ya I'm bad at math

I think where you're gaining or losing numbers is a 9x13 is not divisible EXACTLY by 2" on eithe side. So you have some "extra" cake on a 9x13. A little "extra" cake on TWO 9x13's is resulting in the difference in piece-count that you are seeing.

If you're cutting pieces 1.5x2:
The 9" side would be cut into 6 rows (1-1/2" wide).
The 13" side would be cut into 6 rows (2" wide).
Total: 36 pieces

You'd have half a "row" left on the 13" side that is 1" wide. I assume they are cutting this 1" strip into some leftover pieces to come up with their total of 45.