 # I am not sure if I missed it, but Jay does not explain why the call to puts is returning that empty value?

Why did the call to puts at 9:16 return an empty value? Jay just said it did, but did not explain why.

Thanks! I think I get it now: is it because the method put does not return a value in general, so there is no value to be assigned to the variable number? So the correct way would have been not to use puts in the content of the subtract method, right? That's right. The `puts` method returns `nil`, which is a value that represents the absence of a value. (A little confusing, I know, but that is what it means.) You can see the `nil` value for yourself by running:

```p(puts("hello"))
```

So yes, you want:

```def subtract(first, second)
first - second
end
```

...and NOT:

```def subtract(first, second)
puts first - second # Returns nil!
end
``` ```number = 9
puts number
number = subtract(number,1) # value of the 'number' should be nil, not 8 imho
puts number # prints 8 to the console
puts number.class # class is nil
```

so if the variable 'number' is nil why will it still print a value (8 in this case) to the terminal? if nil is absence of the value, where the value is coming from then? What I'm observing does not match what you are observing... Here are two snippets that include two different definitions for the `subtract` method, to help avoid confusion. I'm also using the `p` method instead of `puts`, because `p` can show `nil` values.

Here it is returning the result of the math operation:

```def subtract(first, second)
first - second
end

number = 9
p number # prints 9 to the console
number = subtract(number,1)
p number # prints 8 to the console
p number.class # class is Integer
```

And here it is returning `nil` because `puts` was used within `subtract` (which you should not do):

```def subtract(first, second)
puts first - second
end

number = 9
p number # prints 9 to the console
number = subtract(number,1) # value of the 'number' IS nil
p number # prints "nil"
p number.class # class is NilClass
```