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

[behi00]

I tried to run your code in pycharm but failed.

import tkinter as tk


class Profit(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title("Profit")
        tk.Label(self,text="Interest rate:").grid(row=0, column=0)
        self.user_input = tk.IntVar(self, "")
        entry = tk.Entry(self, textvariable=self.user_input,width=10,justify=tk.RIGHT,font=("Arial", 10))
        entry.grid(row=0, column=1)
        entry.bind("<Return>", self.calculate)
        # create the  result field
        self.result = tk.StringVar(self, "Result: ")
        tk.Label(self, textvariable=self.result ).grid(row=1, column=0)
    def calculate(self, event):
        self.result.set(f"Result: {72 / self.user_input.get()}")