irrational numbers
it cannot be written as a fraction, there for it is irrational, the test for rational numbers is to try and write it as a fraction, if that is possible without rounding the number, it is a rational number otherwise it is irrational.
if you try to simplify the question you will find that it gives you the square root of 159, which cannot correctly be written as a fraction no matter how hard you try, there for it is a irrational number