If the calculator doesn't calculate your returns, re-check the accuracy of the dates you input and the format (dd-mm-yyyy). Always restart the application in between calculations. Start from the left to right when inputting the data. As this is a tutorial, continue building this and make it better! Some ideas include adding a percentage on your gains, change the emojis based on the results, and/or conditionally render the "USD" and other text elements. I hope you learned something, and thank you for using the crypto calculator! Reach out to me on Twitter at @adshinder if you have any questions!