What are the resources to learn Permutations and Combinations properly?

Question

Websites, books, ebooks, etc. will do. I am very weak in this topic. I have tried a couple of books like Hall and Knight and other textbooks, but still struggle with this topic. Can someone give some real good resources?

Answer 1

I always like www.Khanacademy.org as it has practice questions that give hints and can help you (with practice) learn a topic you are struggling with through sheer repetition.

https://cnx.org/contents/[email protected]:MYP1-SMN@10/Counting-Principles

is the openstax pre-calculus text book. the section is on counting principles. it is an open source interactive text.

Answer 2

In my opinion, the first dozen videos in enumerative combinatorics by Federico Ardila (Link to Lecture 1) are great. For me, I feel his videos have really gave me an intuition for not just combinations, and permutations, but counting techniques in general. I would completely recommend you check it out. Although in lecture $1$ he doesn't really explain binomial coefficients, in lecture $2$ he goes back to the fundamentals and explains everything in detail. I do not recommend skipping lecture $1$.