My guess is that you are thinking of the approximation 22 / 7 ≈ π . The two numbers π and 22 / 7 are not equal, so there's no contradiction in one being rational and the other irrational. Sometimes you use 22 / 7 as a number "fairly close" to π , but: π = 3.14159265... while. 22 / 7 = 3. read more
If you don't know why 22/7 is a rational number, you are not going to understand why $\pi$ is an irrational number. – Gerry Myerson Nov 26 '15 at 11:48 Welcome to the site. read more