Calculator Source Code: from tkinter import * Calc = Tk() Calc.title('Calculator') f = ('arial', 20, 'bold') txt = StringVar() op = '' def btnClick(num): global op op = op + str(num) txt.set(op) def btnClear(): global op op = '' txt.set('') def btnEquals(): global op rst = str(eval(op)) txt.set(rst) op = '' txtDisplay = Entry(Calc, font=f, textvar=txt, bd=30, insertwidth=4, bg='powder blue', justify='right').grid(columnspan = 4) btn7 = Button(Calc, padx=16, bd=8, fg='black', font=f, text='7', bg='powder blue', command=lambda:btnClick(7)).grid(row = 1, column = 0) btn8 = Button(Calc, padx=16, bd=8, fg='black', font=f, text='8', bg='powder blue', command=lambda:btnClick(8)).grid(row = 1, column = 1) btn9 = Button(Calc, padx=16, bd=8, fg='black', font=f, text='9', bg='powder...