Final Design For each week we always want to lay out the final design. As this week is based around the logic rather than how it looks, we’ll lay out the steps necessary to build our calculator:

1. Ask the user for the calculation they would like to perform.
2. Ask the user for the numbers they would like to run the operation on.
3. Check for correct input for the mathematical operation. a. Convert numbers input to floats. b. Perform operation and print result. c. If an there is an error, an print error message.

Creating a Calculator Last week we built a receipt printing program. With the lessons learned from this week, we’re going to be building a simple calculator that accepts user input and outputs the proper result.

Step #1: Ask User for Calculation to Be Performed For each one of these steps, let’s put the code in separate cells. This will allow us to section of the specific steps for our project, making it easier to test each step. The first step is to ask the user to input the mathematical operation to be performed (add, subtract, etc.): Step #2: Ask for Numbers, Alert Order Matters In the cell below step #1, we’ll need to create the next step of our logic. Here, we ask the user to input a couple of numbers and output those numbers for testing purposes: Step #3: Check for correct input The third, and final step, is to try performing the operation. We must convert the user’s input to floating data types. We should assume that they may not enter the proper input, so we need to check whether or not the input is correct. Technically, we don't know how to do this yet, so you could skip it and assume your user will always enter correct input. If you want a more sophisticated approach, Google "python try except".