What is more important number pi or e or I or what?

If you are a banker, you might think e is the most important. Banks can use e to calculate continuous interest. If you are into electronics, you might think that i is most important. Sometimes, the square roots in specialized equations have negative values under the symbol. read more

Pi, simply because it's more often used. Even people who's work has nothing to do with advanced math/physics might need to use it. Like someone building a house. Knowing what "e" means is not that important but knowing pi might be important (unless you are building a a cubical house). read more

e is easier to spell than pi. The character for e, not pi, can be found on a keyboard. ln(pi1) is a really nasty number, but ln(e1) = 1. e is used in calculus whereas pi is used in geometry. read more

Probably pi. While its usage is technically limited, areas and volumes of circular regions are foundational for most uses of e. Exponential growth and decay, of course, use e and not pi, but are far less important to practical mathematics than pi. read more