Endlessly generates a random number and shows it in a Tkinter window.

tkinter_random_number.py

import tkinter as tk
import random


class Random(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.title("Random")

        self.variable = tk.IntVar()
        label = tk.Label(self, textvariable=self.variable, font=("courier", 69))
        label.pack(fill="both", expand=True)

        self.do_random()

    def do_random(self, interval=100):
        self.variable.set(random.randint(0, 99999))

        self.after(interval, self.do_random)


def main():
    r = Random()
    r.mainloop()

if __name__ == "__main__":
    main()