Made to Order

This boggled me.

Made to Order

I wonder how he figured that out. Is it something that is well known?

I never heard of it before, and I can't imagine that it's something you would accidentally discover, so somebody must have started from the answer they wanted and worked back to the number that gets there. But you would need something slightly specialized to do that. Then again, the kind of nerd that would think of doing it is just the sort of nerd who would have that access.