GoKawiilStudy finds only 129 English words break the simple 'a vs an' spelling rule
An analysis of 32,455 words examined whether choosing 'a' or 'an' can be reliably determined just by checking a word's first letter versus its actual pronunciation. The author built visualizations and a trie-based tool to identify exceptions, finding that only 129 words—like 'unicorn' and 'hour'—require checking pronunciation rather than spelling.