Glue test

from tkinter import *

class MathButton:
    def __init__(self, action):

        self.but = Button(text=action, width=10, command=self.math)
        self.operator = action
        self.but.pack()



    def math(self):
        try:
            n1= float(ent_n1.get())
            n2= float(ent_n2.get())
        except ValueError:
            lab_result['text'] ='Error'
        else:
            if self.operator == 'S':

                lab_result['text'] = n1 * n2


root=Tk()
n1= Label(text= 'Введите ширину детали', font='Arial 12', bd=15)
n1.pack()
ent_n1 = Entry(width=10)
ent_n1.pack()
n2= Label(text= 'Введите длинну детали', font='Arial 12')
n2.pack()
ent_n2 = Entry(width=10)
ent_n2.pack()

n3= Label(text= 'Площадь детали:')
n3.pack()
but_summa = MathButton('S')
lab_result = Label(width = 15)
lab_result.pack()


root.mainloop()