Help!

I don't know what you are doing wrong either, since you didn't share your code! But I can give you some general hints. Each task of the challenge asks you to implement a different method of the calculator object. The add method is already provided, as was shown in the video. It looks like this:

  add: function(value) {
    this.sum += value;        // <-- this code was added in the video to implement the add method
  }

Notice the plus (+) sign in the added code? Now if you were to add a line just like that but with a different sign you would be implementing a different kind of method. You know which symbols represent subtract, multiply, and divide, right? For each task of the challenge, try filling in the requested method with a line of code that has the symbol associated with that function instead of the plus sign.

If this hint doesn't get you through the challenge, try posting the code you were using that would not pass the "check work" test.