👉 In mathematics and computer science, a "faculative" is a term that refers to an expression or formula that contains a variable in its definition. It is often used when dealing with mathematical expressions where there are multiple variables involved.
For example:
```python
def factorial(n):
if n == 0: return 1
else: return n
factorial(n-1)
```
In this code, the `factorial` function takes an integer `n` as input and returns