Zacryon

I ended up not getting it because the whiteboard guy didn’t like that I didn’t remember the formula for an n-dimensional plane off the top of my head.

What do they want? A walking wikipedia or someone who knows how to look up necessary stuff, evaluate it and put it appropriately into practise?

Don't participate in such a process and the problem solves itself (unless you are very desperate). As long as companies find some idiot who jumps through these hoops, they will continue to do this. When they realize that they are deterring candidates with this shitty process, they might start changing it.

That's a complicated way of saying that Microsoft recommends switching to Linux. /j

Have you tried Ecosia?