The answer is no to the question, is -10 an irrational number? As we are going to discuss that irrational numbers are the real numbers which are not rational, which means they cannot be expressed in the form of a fraction a/b, where a and b are integers and b is not equal to 0. The reason why the answer is a no to the question, is -10 an irrational number, is, because we can represent -10 as a fraction, i.e., -50/5, -20/2, -100/10 etc.