Wow. In one of my classes, I'm helping someone with a sweater project. It's from a popular book, and one of the great features of this particular design is that it's easily and cleverly custom-fit. The body is constructed in panels - the central panels are the same for all sizes, and customization is done through the use of variable width side panels.
All it needs is a couple of measurements and a bit of arithmetic.
My students know about my secret past as a mathematician, so anything like this gets handed off to me. I'm happy to do it, it helps my students, and it teaches me more about garment construction.
I spent a few minutes looking at the calculations and the pattern, and couldn't for the life of me figure it out. And then I Googled for errata.
Yeah. It turns out that through what must have been a terrible typesetting mistake, all of the minus signs in the formulas had been changed to division symbols. All of them. About 15, in total. No wonder my numbers weren't working.
So: VERY IMPORTANT NOTE to self, and everyone else: before you start any pattern, Google for errata. If I'd gone with the calculations as printed in the book, the sweater would have been significantly too small.