Search a few thousand lines of code to find where I divided instead of multiplied

Explain the problem to someone else, even if they know nothing about programming. Somehow, describing the issue out loud triggers thought patterns that simply reading your code doesn’t, and they frequently lead to a solution.

Sleep on it. Can't tell how many time i've fallen asleep and woken up to a solved problem with no idea how the code i sleep-wrote works but it works so don't touch it.

Post it on https://stackoverflow.com