from Tkinter import * from math import * def calc(): result = "= " + str(eval(expression.get())) label.config(text = result) root = Tk() frame = Frame(root) label = Label(frame) entry = Entry(frame) expression = StringVar() entry["textvariable"] = expression button = Button(frame, text = "=", command = calc) frame.pack() entry.pack() label.pack(side=LEFT) button.pack(side=RIGHT) frame.mainloop()