Here is the part of the math problem I'm trying to understand.
$A=\{x|x \in IN: x^3>25 \,\, and \,\, x^4<264\}$
I know $N$ is used to denote Natural Numbers. But I'm unfamiliar with $IN$. I have done Google searches, but I didn't find anything helpful.
This part of the math problem is from a printed textbook. So I was wondering whether this were a typo.