The hardest question a child ever asked me led to the answer I consider my best.
I was asked what is the difference between letters and numbers.
My answer…
Letters get arranged together to make words, and ell stories. Stories about people, animals, places, all come from sorting letters.
Numbers also tell a story. They tell how big, how small, how new, how old.
With this in mind, my answer to this question is we invented language, symbols, measuring tools to share knowledge. We invented the symbols found on a calculator to better understand what exists, and what we can do with what exists.
A light-year is something which existed before humans, but we calculated it and use those calculations. Math is a language we use to share what we know, and to learn what we don’t know yet.