Set the calculator to add or subtract

- [Instructor] The next buttons we're going to set up…are the add and subtract buttons.…So we're going to handle all the code…inside of the change mode method.…So find that in your code.…Mine is on line 54, but of course,…yours might be on a different line.…So, the first thing we need to do when we change the mode,…is we set current mode equal to the mode passed in.…So when the user presses the plus button,…CalculatorMode.Add is set to change mode,…and when they press the minus button,…CalculatorMode.Subtract is set to change mode.…

So let's scroll down.…So we changed the current mode,…so we're storing the mode that the user set,…and then we set lastButtonWasMode equal to true.…Another place where we need to handle the CalculatorMode…is inside of didPressNumber.…Inside of didPressNumber,…we want to see if the last button was mode.…So imagine the user types in a certain amount of numbers,…they type in five, and then they press the plus button…and we run change mode.…

And then they press a six.…What should appear on the screen?…