I almost didn't take the test at all, so thank you for asking.
I applied on a Sunday night, kind of on a whim. I work in hospital operations and haven't done real math since sophomore stats. When the link came on Wednesday I did a practice set and got 41%. I really told myself Bain isn't for people like me.
My sister said, "Buy one module. It's $20, that's lunch." So I did the Numerical module over two evenings, about 90 questions. 41, then 63, then 74. The shortcuts in the explanations were things nobody ever taught me.
I passed. I have my first interview with the Denver office in two weeks, and I'm (mostly) excited instead of terrified.
The cheat sheet I made is taped to my monitor at work.