Why is the program not running? Is there a logical or syntax problem?

[deanhystad]

Your indentation is all over the place. This is correct:

import tkinter as tk
 
class Profit:
    def __init__(self, master):

This is wrong:

        self.calculate_button.grid(row=2, column=0)
      def rule(master):   #<- Should be same indentation as __init__.  Should also be blank line before def rule(master):
      return 72/master

# Should be indented 4 space from line above.

And this is wrong:

# create the main window and profit object
 root = tk.Tk()     # <- Should be no spaces, not 1
 pro = Profit(root)
 root.mainloop()

Your rule method is not written correctly (see my first post). It is likely you'll need to change the code where you call the method too.