Why is pi irrational?

Answer 1

Pi can't be expressed as a fraction (a ratio of two integers), which makes it irrational. Another way to say it. Pi (π) is an irrational number; it's trancendent. The mathematical proof that pi is irrational can be viewed by using the link to the Wikipedia article on exactly this topic. The challenge is that to understand the proof, one needs some familiarity with integral calculus. Short of that, one would probably have to just accept the fact that pi is transcendent and that it has been proved. (Pi was suspected to be irrational from ancient times, but it was actually proved to be in the 1700's.)