from tkinter import *
def Calculate():
  a1 = int(text1.get('1.0', END)) # 从行首取到行尾
  a2 = int(text2.get('1.0', END))
  a3 = a1 + a2
  text3.delete('1.0', END)
  text3.insert(INSERT, a3)
 
root = Tk()
root.title('myTitle')
label1 = Label(root, text = 'First Number:')
label1.grid(row = 0, column = 0)
text1 = Text(root, width = 30, height = 1)
text1.grid(row= 1, column = 0)
label2 = Label(root, text = 'Second Number:')
label2.grid(row = 2, column = 0)
text2 = Text(root, width = 30, height = 1)
text2.grid(row = 3, column = 0)
label3 = Label(root, text = 'Result:')
label3.grid(row = 4, column = 0)
text3 = Text(root, width = 30, height = 1)
text3.grid(row = 5, column = 0)
button1 = Button(root, text = 'Calculate', command = Calculate)
button1.grid(row = 6, column = 0)
mainloop()