from tkinter import *
from threading import Timer
from random import randint
def autoText():
....global timer,var
....var.set(str(randint(1,100)))
....timer = Timer(1, autoText)
....timer.start()
win=Tk()
var = StringVar()
var.set('1')
lb1 = Label(textvariable = var,width = 10,height = 3 )
lb1.pack()
timer = Timer(1, autoText)
timer.start()
win.mainloop()