In this video I show a simple proof that you can sort n distinct objects in n! ways. This is very useful and important to understand especially if you are interested in statistics or even poker. Watch

In this video I introduce the concept of factorials and do various examples on multiplying and dividing them out. I also show a quick proof showing that 4 distinct objects can be sorted in 4! = 4·3·2·1

Hi there. In this math post, I take a look on the number of key arrangements (permutations) on a circular keychain. I came across this type of problem from my work. It did not look familiar to me as it