title: How to make label and entry start blank
body: <p>Any idea on how to make all the entry and labels in my GUI start blank but then update when the calculate function happens? They currently start with a 0. I have tried many things but nothing has worked. </p>
  
  <p>Here is code: </p>
  
  <pre><code>from tkinter import *
  
  root = Tk(className="Page Calculator")
  root.title("PgCalc")
  read = IntVar()
  total = IntVar()
  left = IntVar()
  percent = IntVar()
  
  def calculate(event=None):
      try:
          left.set(total.get() - read.get())
          percent.set(int(read.get()*100/total.get()))
      except ZeroDivisionError:
          print("ZeroDivisionError")
      else:
          print()
  
  root.bind('&lt;Return&gt;', calculate)
  
  read_label = Label(root,text="Pages Read:")
  read_label.grid(column=1, row=1)
  
  read_entry = Entry(root, width=8, textvariable=read)
  read_entry.grid(column=2, row=1)
  read_entry.focus()
  
  total_label = Label(root,text="Total Pages:")
  total_label.grid(column=1, row=2)
  
  total_entry = Entry(root, width=8, textvariable=total)
  total_entry.grid(column=2, row=2)
  
  
  calculate_button = Button(root,text="Calculate",command= calculate)
  calculate_button.grid(column=2, row=3)
  
  percent_label = Label(root,text="Percent Finished:")
  percent_label.grid(column=1, row=4)
  
  left_label = Label(root,text="Pages Left:")
  left_label.grid(column=1, row=5)
  
  percentresult_label = Label(root,textvariable=percent)
  percentresult_label.grid(column=2, row=4)
  
  leftresult_label = Label(root,textvariable=left)
  leftresult_label.grid(column=2, row=5)
  
  root.mainloop()
  </code></pre>