1.) Referred for callback of clear button: https://www.youtube.com/watch?v=782_MBAZRuw
2.) Referred For Custom Dialog: https://www.mkyong.com/android/android-custom-dialog-example/
3.) Referred For setting up scale: https://stackoverflow.com/questions/33889019/bigdecimal-divide-with-a-large-number-of-decimal-places