One of my favorite short stories is Spell My Name With An S, by Isaac Asimov, published in Nine Tomorrows. It is a story I read decades ago yet it stays with me:
“Marshall Zebatinsky felt foolish….” (Read the whole story here.)
It is about a nuclear physicist who visits a numerologist because his career is not moving forward. The numerologist suggests a tiny change: spelling Zebatinsky with an ‘s’: Sebatinsky. This tiny input starts a chain of events (unknown to Zebatinsky/Sebatinsky) which averts the world from nuclear annihilation. And yet that’s not the end of the story….read the whole story here.