Answer:
The first one is by using your mind. If you know that factorial of any non negative integer denoted by n!
defined as
n!=n(n−1)(n−2)⋯3⋅2⋅1
then 5!=5∗4∗3∗2∗1. You can calculate it in your mind which will give you 5!=120.
That's it.
The next method is using your calculator. In my calculator Casio fx-991es, I pressed 5 and then shift+x−1
button and I got 120. Similarly, you can use Google to calculate it like I did and got this.
Step-by-step explanation:
