Factorials are numbers multiples by the integers before it in descending order until 1. E.g. 7! = 7x6x5x4x3x2x1.

This is part of the Prelim Maths Extension 1 Syllabus from the topic Combinatorics: Working with Combinatorics. In this post, we will explore Permutations and combinations Factorials. Here we will learn to use factorial notation.

##### Part 1