All language subtitles for 4. Example 2 - Factorial

All right, so that's another example in our Recursions section.

And in this video, what we are going to do is to write a function that received some natural number

NUM and returns there, factorial of this number.

And for those of you who is not so familiar with what factorial is, let's explain it in simple terms.

So a factorial by its definition is just a mathematical operation and is defined to be as the multiplication

of all natural numbers from one up to a given number.

So very similar to how we used to find the sum of all the numbers from one up to number.

The factorial simply finds the multiplication of all the numbers of all the natural numbers from one

to a given number.

So, for example, if we want to calculate the factorial for numskulls two three, then our recursive

function should return the result of one multiplied by two, multiplied by three, which is a total

of six.

And if we want to calculate the factorial for nummy equals two five, then our recursive function should

return the result of one multiplied by two and so on, up to five, which is a total of one hundred

and twenty.

So basically we can say that the function for a given NUM should return the following result of one

multiplied by two, multiplied by three and so on.

Up until a given num so num minus one will be our one element before the last one.

And num will be our last element in this multiplication factorial formula.

Not so complicated.

Right.

And it's basically it's pretty similar to the previous example.

We can see that the only thing that changed between these example to the previous one is that we just

instead of using the addition operator, we are just using their multiplication.

So also very similar to the previous question.

So you will be able to write the factorial function with ease.

I suggest using the same approach as we did previously and just to show you the multiplication from

left to right.

So instead of taking a look at this formula from the left to the right.

Right from one multiplied by two and so on, we will look at from right to left, which is num multiplied

by num minus one and so on and so forth.

You've got the idea the result will be the same.

Would it change anything, just the order that would look at the multiplication.

But the overall result is going to be the same.

And now it's time for some Hanzo in our programming language.

So let's go.