I spent about a week building factorcalculator.org — a free math tool that finds the factors, factor pairs, prime factorization and divisors of any number, with the full working shown instead of just an answer. Six hand-built calculator pages, plus 1,200 generated pages ( /factors-of-1/ through /factors-of-1200/ ). Next.js 16 App Router, Tailwind, static export, deployed to Cloudflare Pages. Most of it went fine. Three things did not, and two of them are the kind of bug where everythin...