Earlier quoted context omitted.
My father was the defacto Excel developer in his office and used to have vivid dreams that consisted solely of him writing out the code for some problem he'd been working on. Then he'd wake up and forget the lot.
this. the trick is when u cant remember to stop there, and dont worry or force it, about 10 mins later the answer will come to u.
sadly, i use this same technique on the toilet.