from tkinter import *
def ha_one(event):
    tex1.insert(END, "1")
def ha_two(event):
    tex1.insert(END, "2")
def sum1(event):
    tex1.insert(END, "+")
def eq1(event):
    c = a + b
    tex1.delete()
    tex1.insert(c)
root = Tk()
if sum1 == True:
    a = int(tex1.get())
if eq1 == True:
    b = int(tex1.get())
fra0 = Frame(root, width=400, height=50, bg="#ffe240")
fra1 = Frame(root, width=400, height=150, bg="#ffeed0")
tex1 = Text(fra0, width=30, height=3,
            font="Verdana 12", wrap=WORD)
but1 = Button(fra1, text="1")
but2 = Button(fra1, text="2")
butSum = Button(fra1, text="+")
butEqual = Button(fra1, text="=")
but1.bind("<Button-1>", ha_one)
but2.bind("<Button-1>", ha_two)
butSum.bind("<Button-1>", sum1)
butEqual.bind("<Button-1>", eq1)
fra0.pack()
tex1.pack()
fra1.pack()
but1.pack()
but2.pack()
butSum.pack()
butEqual.pack()
root.mainloop()

 [code python][/code]

tex1.insert©

root = Tk()

# -*- coding: utf-8 -*-
from Tkinter import *
class CalcButton(Button):
    def __init__(self,*args,**kw):
        Button.__init__(self,*args,**kw)
        self.__val=''
    @property
    def Value(self):
        return self.__val
    @Value.setter
    def Value(self,val):
        self.__val=str(val)
    def set_command(self,obj):
        self.configure(command=lambda : obj.text.insert(END,self.Value))
class Calc(object):
    def __init__(self, master):
        self.master=master
        self.COMMANDS=['+','-','*','/','.']
        self.text_frame=Frame(master=self.master)
        self.text_frame.pack()
        self.text=Text(master=self.text_frame, width=30, height=3, font="Verdana 12")
        self.text.pack()
        self.int_common_frame=Frame(master=self.master)
        self.int_common_frame.pack(side=LEFT, padx=10)
        self.int_frames=[ Frame(master=self.int_common_frame) for _ in range(4) ]
        for fr in self.int_frames:
            fr.pack()
        self.commands_frame=Frame(master=self.master)
        self.commands_frame.pack(side=LEFT, padx=10, pady=10)
        self.int_buttons=[CalcButton( master=self.int_frames[i/3], text=i)  for i in range(10)]
        self.command_buttons=[CalcButton(master=self.commands_frame, text=c) for c in self.COMMANDS]
        self.pac_buttons(self.int_buttons, LEFT)
        self.pac_buttons(self.command_buttons,BOTTOM)
        self.enter_frame=Frame(master=self.master)
        self.enter_frame.pack(side=LEFT)
        self.enter_button=Button(master=self.enter_frame, text='=', command=self.calculate)
        self.enter_button.pack()
        self.clear_button=Button(master=self.enter_frame, text=' C ', command=self.clear)
        self.clear_button.pack()
    def pac_buttons(self,l,side):
        for bt in l:
            bt.Value=bt.config()['text'][4]
            bt.set_command(self)
            bt.pack(side=side)
    def calculate(self):
        try:
            result=eval(self.text.get(1.0,END))
        except SyntaxError:pass
        except ZeroDivisionError:
            self.text.delete(1.0,END)
            self.text.insert(END,u'На ноль делишь, сабака!')
        else:
            self.text.delete(1.0,END)
            self.text.insert(END,result)
    def clear(self):
         self.text.delete(1.0,END)
if __name__=="__main__":
    root = Tk()
    app = Calc(root)
    root.mainloop()