Why does the correct answer include an "=" sign? I never saw this in the video.

Hi there! To be honest, I'm not sure why your code passed other than to say that every Ruby block returns a value. However, the challenge never asked you to print anything. It asked you to return a value. At 0:38 of the preceding video the return statement is first used. It is, of course, entirely different than the puts statement.

The answer it was expecting (I believe) was:

def mod(a, b)
  return a % b
end

I know that it has something to do with "implicit return" values in Ruby, but I'm far from an expert. I do know that because every Ruby block returns a value, it would seem to me that the result in your second variant is assigned to puts which results in the correct value being returned while the puts a % b probably results in an object being returned.

Hope this helps!

Technically all you need is:

def mod(a, b)
  a % b
end

Remember the return is implied, and it is asking to "return" not to print, so you do not need the "put" keyword, you could use the "return" keyword instead. Cheers.

= is an assignment operator

so you have assigned a variable called puts to the value of a % b