Magic Trick based on modulos

magictrick.py

from tkinter import *
from tkinter import scrolledtext
from tkinter import messagebox
from tkinter.ttk import Progressbar
from tkinter import filedialog
from tkinter import Menu

window = Tk()
window.title("Magic Trick")

window.geometry('620x330')
lbl = Label(window, text = "Steps to follow:", font = ("System",20))
lbl.grid(column = 0, row = 4, columnspan = 22)

step1 = Label(window, text = "1. Think of any 4 digit number that has at least two unique digits (e.g. 2222 is not accepted!)", font = ("System",14))
step1.grid(column = 0, row = 8, columnspan = 22)

step2 = Label(window, text = "2. Reverse the 4 digit number. (e.g. 1234 -> 4321)", font = ("System",14))
step2.grid(column = 0, row = 10, columnspan = 22)

step3 = Label(window, text = "3. Subtract the bigger number from the smaller number (e.g. 4321 - 1234 = 3087)", font = ("System",14))
step3.grid(column = 0, row = 12, columnspan = 22)

step4 = Label(window, text = "4. Cross out ONE of the nonzero digits. (e.g. 3087 -> cross out 3, 8, or 7)", font = ("System",14))
step4.grid(column = 0, row = 14, columnspan = 22)

step5 = Label(window, text = "5. Enter the remaining 3 digits (in any order) and I will guess the digit you crossed out!", font = ("System",14))
step5.grid(column = 0, row = 16, columnspan = 22)

firstdigit = Entry(window, width = 1, font = ("System", 30))
firstdigit.grid(column = 10, row = 20)

seconddigit = Entry(window, width = 1, font = ("System", 30))
seconddigit.grid(column = 11, row = 20)

thirddigit = Entry(window, width = 1, font = ("System", 30))
thirddigit.grid(column = 12, row = 20)

msglbl = Label(window, text = "", font = ("System", 20))
msglbl.grid(column = 0, row = 40, columnspan = 22)

result = Label(window, text = "", font = ("System", 40))
result.grid(column = 0, row = 44, columnspan = 22)

def clicked():
    msglbl.configure(text = "The number that you crossed out is")
    sum = int(firstdigit.get()) + int(seconddigit.get()) + int(thirddigit.get())
    div9 = sum // 9
    r = (div9 + 1) * 9
    final = r - sum
    result.configure(text = str(final))

guess = Button(window, text = "Guess!", command = clicked, font = ("System", 20), width = 12)
guess.grid(column = 1, row = 36, columnspan = 24)

window.mainloop()

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