Sumator

import tkinter as tk

class Application(tk.Frame) :
    def __init__(self, master=None):
        super().__init__(master)

        self.pack()
        self.create_widgets()

    def create_widgets(self):
        #create widgets
        self.firstNumberEntry = tk.Entry()
        self.plusSign = tk.Label(text="+")
        self.secondNumberEntry = tk.Entry()
        self.equalSign = tk.Label(text="=")
        self.resultLabel = tk.Label(text="Result...", bg="green", fg="white")
        self.calculateButton = tk.Button(text="Calculate", command=self.calculate)

        # place widgets
        self.firstNumberEntry.pack(side="left")
        self.plusSign.pack(side="left")
        self.secondNumberEntry.pack(side="left")
        self.equalSign.pack(side="left")
        self.resultLabel.pack(side="left")
        self.calculateButton.pack(side="left")

    def calculate(self):
            first_value = float(self.firstNumberEntry.get())
            second_value = float(self.secondNumberEntry.get())
            result = first_value + second_value
            self.resultLabel.config(text=str(result), bg="green", fg="white")



# create the application
app = Application()
app.master.title("Sumator")
app.master.minsize(width=100, height=50)

# start the program
app.mainloop()