why typeof NaN is a 'number' ?

Question

console.log(typeof NaN);
//number
Why!! , NaN 'means Not a Number'.

Answer 1

Well it's hard to explain but I will try:
NaN is result of some calculation, that negate mathematical logic. For example 1/0 (1 divided by 0). It cannot be represented mathematicly (is this a word?), but for computer it's still a number, perhaps too complex to express, so programmers had an idea to make it easier for computer by introducing NaN.
In shortcut: NaN is still a number, just too complex, or too big to express.