I had to work on a coding project with a serious geometric problem in the core, and no amount of thinking over code itself could help, whereas on paper, I could

I had to work on a coding project with a serious geometric problem in the core, and no amount of thinking over code itself could help, whereas on paper, I could find the solution easily. And implementing it in code didn't progress, until I wrote down all the formulae, in sequence, on paper too.