Determine page number and offsets for address references


I’m working on learning operating systems and I’ve come across a strange question that I don’t know how to answer.

The question is:

Assuming a 1-KB page size, what are the page numbers and offsets for the following address references (provided as decimal numbers)?

21205

The notes and slides I have are very confusing and I can’t find anything quite like this from my searches. I understand that a 1KB page size means that it’s 2^10 but what do I do after that exactly? Most descriptions I see involve splitting that in half and using the first half as your offset and the other half as the page number but then I see others saying not to do this and my notes, as I mentioned, are useless. I’m sure this is extremely easy but I feel like I’ve been given only 1/3 of the knowledge needed.

Any help would be greatly appreciated!