How exactly do I solve this?

Question

I am trying to do the practice exercise at the end of the For loop section of Introduction to C#. But I am confused as hell on the right code to perform the task it wants.

The factorial of a number N is equal to 1 * 2 * 3 * ... * N
For example, the factorial of 5 is 1 * 2 * 3 * 4 * 5 = 120.
The given program takes a number from the input.

Task
Create a program to calculate and output the factorial of that input number.

Answer 1

You could try it with recursion,
I am not familiar with C# sytantx but a sudo code might help you.
//Sudo code:
Int fact=1;
Function factorial(int a){
fact=a*factorial(a-1)
}

Answer 2

James Welsh start with the result variable initialized to 1. Use a for loop that increments the loop index from 1 through N. Inside the loop, multiply the result value by the loop index and save it back into the result variable. After the loop, print the result to the console.