from tkinter import *

root = Tk()
root.title("Simple Calculator")

e = Entry(root, width = 35, borderwidth = 5)
e.grid(row = 0, column = 0, columnspan = 3, padx = 10, pady = 10)

def button_click(number):
    # e.delete(0, END)
    current = e.get()
    e.delete(0, END)
    e.insert(0, str(current) + str(number))

def button_clear():
    e.delete(0, END)

def button_add():
    first_number = e.get()
    global f_num
    global math
    math = 'addition'
    f_num = int(first_number)
    e.delete(0, END)

def button_subtract():
    first_number = e.get()
    global f_num
    global math
    math = 'subtraction'
    f_num = int(first_number)
    e.delete(0, END)

def button_multiply():
    first_number = e.get()
    global f_num
    global math
    math = 'multiplication'
    f_num = int(first_number)
    e.delete(0, END)
    
def button_divide():
    first_number = e.get()
    global f_num
    global math
    math = 'division'
    f_num = int(first_number)
    e.delete(0, END)

def button_equal():
    second_number = e.get()
    e.delete(0, END)

    if math == 'addition':
        e.insert(0, f_num + int(second_number))
    if math == 'subtraction':
        e.insert(0, f_num - int(second_number))
    if math == 'multiplication':
        e.insert(0, f_num * int(second_number))
    if math == 'division':
        e.insert(0, f_num / int(second_number))  

# Define the buttons

button_1 = Button(root, text='1', padx = 40, pady = 20, command = lambda: button_click(1))
button_2 = Button(root, text='2', padx = 40, pady = 20, command = lambda: button_click(2))
button_3 = Button(root, text='3', padx = 40, pady = 20, command = lambda: button_click(3))
button_4 = Button(root, text='4', padx = 40, pady = 20, command = lambda: button_click(4))
button_5 = Button(root, text='5', padx = 40, pady = 20, command = lambda: button_click(5))
button_6 = Button(root, text='6', padx = 40, pady = 20, command = lambda: button_click(6))
button_7 = Button(root, text='7', padx = 40, pady = 20, command = lambda: button_click(7))
button_8 = Button(root, text='8', padx = 40, pady = 20, command = lambda: button_click(8))
button_9 = Button(root, text='9', padx = 40, pady = 20, command = lambda: button_click(9))
button_0 = Button(root, text='0', padx = 40, pady = 20, command = lambda: button_click(0))
button_add = Button(root, text='+', padx = 39, pady = 20, command = button_add)
button_subtract = Button(root, text='-', padx = 41, pady = 20, command = button_subtract)
button_multiply = Button(root, text='*', padx = 40, pady = 20, command = button_multiply)
button_divide = Button(root, text='/', padx = 40, pady = 20, command = button_divide)
button_equal = Button(root, text='=', padx = 88, pady = 20, command = button_equal)
button_clear = Button(root, text='Clear', padx = 78, pady = 20, command = button_clear)

# Put the butons on the screen

button_1.grid(row=3, column=0)
button_2.grid(row=3, column=1)
button_3.grid(row=3, column=2)

button_4.grid(row=2, column=0)
button_5.grid(row=2, column=1)
button_6.grid(row=2, column=2)

button_7.grid(row=1, column=0)
button_8.grid(row=1, column=1)
button_9.grid(row=1, column=2)

button_0.grid(row=4, column=0)
button_clear.grid(row=4, column=1, columnspan=2)
button_add.grid(row=5, column=0)
button_equal.grid(row=5, column=1, columnspan=2)

button_subtract.grid(row=6, column=0)
button_multiply.grid(row=6, column=1)
button_divide.grid(row=6, column=2)

root.mainloop()