title: TypeError: unsupported operand type(s) for +=: 'int' and 'str'. I have been trying to debug this error for 20 minutes
body: <p>Nothing I do seems to work. I clicked like 10 links on the subject, and nothing worked to solve my issue. Sorry for the long code.</p>
  <pre><code>from tkinter import *
  
  
  numbers = {}
  
  
  root = Tk()
  
  root.title(&quot;Calculator&quot;)
  
  
  display_numbers = Entry(root, width=30)
  
  display_numbers.grid(column=0, row=0, columnspan=2)
  
  
  def clicked_number(value):
      print(value)
      display_numbers.insert(len(display_numbers.get()), value)
  
  
  def clicked_clear():
      print(&quot;cleared&quot;)
      display_numbers.delete(0, END)
  
  
  def clicked_add():
      print(&quot;added&quot;)
      display_numbers.delete(0, END)
      number = display_numbers.get()
      numbers[len(numbers)] = number
  
  
  def clicked_equals():
      summed = 0
      for number in numbers:
          summed += str(numbers.get(number))
      display_numbers.delete(0, END)
      display_numbers.insert(0, summed)
  
  
  button_1 = Button(root, text=&quot;1&quot;, padx=40, pady=30, command=lambda: clicked_number(1))
  button_2 = Button(root, text=&quot;2&quot;, padx=40, pady=30, command=lambda: clicked_number(2))
  button_3 = Button(root, text=&quot;3&quot;, padx=40, pady=30, command=lambda: clicked_number(3))
  
  button_4 = Button(root, text=&quot;4&quot;, padx=40, pady=30, command=lambda: clicked_number(4))
  button_5 = Button(root, text=&quot;5&quot;, padx=40, pady=30, command=lambda: clicked_number(5))
  button_6 = Button(root, text=&quot;6&quot;, padx=40, pady=30, command=lambda: clicked_number(6))
  
  button_7 = Button(root, text=&quot;7&quot;, padx=40, pady=30, command=lambda: clicked_number(7))
  button_8 = Button(root, text=&quot;8&quot;, padx=40, pady=30, command=lambda: clicked_number(8))
  button_9 = Button(root, text=&quot;9&quot;, padx=40, pady=30, command=lambda: clicked_number(9))
  
  button_0 = Button(root, text=&quot;0&quot;, padx=40, pady=30, command=lambda: clicked_number(0))
  button_clear = Button(root, text=&quot;Clear&quot;, padx=80, pady=30, command=clicked_clear)
  
  button_add = Button(root, text=&quot;+&quot;, padx=40, pady=30, command=clicked_add)
  button_equals = Button(root, text=&quot;=&quot;, padx=40, pady=30, command=clicked_equals)
  
  
  button_7.grid(column=0, row=1)
  button_8.grid(column=1, row=1)
  button_9.grid(column=2, row=1)
  
  button_4.grid(column=0, row=2)
  button_5.grid(column=1, row=2)
  button_6.grid(column=2, row=2)
  
  button_1.grid(column=0, row=3)
  button_2.grid(column=1, row=3)
  button_3.grid(column=2, row=3)
  
  button_0.grid(column=0, row=4)
  button_clear.grid(column=1, row=4, columnspan=2)
  
  button_add.grid(column=0, row=5)
  button_equals.grid(column=1, row=5)
  
  
  root.mainloop()
  </code></pre>
  <p>Here is the entire error message:</p>
  <pre><code>Exception in Tkinter callback
  Traceback (most recent call last):
    File &quot;C:\Users\itsuw\AppData\Local\Programs\Python\Python38-32\lib\tkinter\__init__.py&quot;, line 1883, in __call__
      return self.func(*args)
    File &quot;C:/Users/itsuw/PycharmProjects/tkintercalc/main.py&quot;, line 37, in clicked_equals
      summed += str(numbers.get(number))
  TypeError: unsupported operand type(s) for +=: 'int' and 'str'
  </code></pre>