# Proof a number is irrational

## Main Question or Discussion Point

I've been thinking about pi^e lately, and trying to prove that it is irrational. By rewriting e as 1+1+1/2+1/3!+...+1/n! I got it to pi^2*pi^(1/2)*pi^(1/3!)*...*pi^(1/n!), and proved that each of these terms is irrational. I'm stuck when it comes to showing that multiplied together these numbers are irrational. Any ideas?

## Answers and Replies

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Hurkyl
Staff Emeritus
Science Advisor
Gold Member
Although we know a lot about certain forms, proving numbers irrational is generally a very, very hard thing to do. For example, I think we don't even know whether or not pi+e is irrational!

CRGreathouse
Science Advisor
Homework Helper
I don't think that is a workable approach, since it's possible to form a rational number as the series where the partial sums are all irrational.

No, we do not know if pi+e is irrational, but I don't think that one is very interesting. I think it would be interesting to know if γ(gamma) is irrational though.