22/7 is a irrational number

today in my linear algebra class, the professor was introducing complex numbers and was speaking about the sets of numbers like natural, integers, etc… He then wrote that 22/7 is irrational and when questioned why it is not a rational because it can be written as a fraction he said it is much deeper than that and he is just being brief. He frequently gets things wrong but he seemed persistent on this one, am i missing something or was he just flat out incorrect.