Zachy's law was created on January 9th, when Zach Bruhn was writing the first part of the 21 story which you just came from.
Because he was writing a story, he realized something.
There where 2 numbers in the equation.
If you add 2 to the equation, it was 21.
Simple. Zach would later become famous for his work.
Little did he know, the man who created this equation had already solved it.
And Zachy's law, was already made up.