A calculator in Python ..

 Building a simple calculator in Python..

..without installing any libraries ..

The source code ..

from tkinter import *
#tkinter-preinstalled

root=Tk()
root.title('calculator')

e=Entry(root,width=35,borderwidth=5,)
e.grid(row=0,column=0,columnspan=3,padx=10,pady=10)
#no pack function when grid is there..


#defining the functions of the commands in our buttons
def button_click(number):

    current=e.get()
    e.delete(0,END)
    e.insert(0,str(current) +str(number))

def button_clear():
    e.delete(0, END)

def button_add():
    first_number=e.get()
    global f_num
    global math
    math='addition'
    f_num=int(first_number)
    e.delete(0,END)

def button_equalto():
    second_number=e.get()
    e.delete(0,END)

    if math == "addition":
        e.insert(0, f_num + int(second_number))

    if math == "subtraction":
        e.insert(0, f_num - int(second_number))

    if math == "multiplication":
        e.insert(0, f_num * int(second_number))

    if math == "division":
        e.insert(0, f_num / int(second_number))





def button_subtract():
    first_number = e.get()
    global f_num
    global math
    math = 'subtraction'
    f_num = int(first_number)
    e.delete(0, END)

def button_multiplication():
    first_number = e.get()
    global f_num
    global math
    math = 'multiplication'
    f_num = int(first_number)
    e.delete(0, END)

def button_divide():
    first_number = e.get()
    global f_num
    global math
    math = 'division'
    f_num = int(first_number)
    e.delete(0, END)



#creating the buttons for our calculator
button_1=Button(root,text='1',padx=40,pady=10,command=lambda : button_click(1))
button_2=Button(root,text='2',padx=40,pady=10,command=lambda : button_click(2))
button_3=Button(root,text='3',padx=40,pady=10,command=lambda : button_click(3))
button_4=Button(root,text='4',padx=40,pady=10,command=lambda : button_click(4))
button_5=Button(root,text='5',padx=40,pady=10,command=lambda : button_click(5))
button_6=Button(root,text='6',padx=40,pady=10,command=lambda: button_click(6))
button_7=Button(root,text='7',padx=40,pady=10,command=lambda: button_click(7))
button_8=Button(root,text='8',padx=40,pady=10,command=lambda: button_click(8))
button_9=Button(root,text='9',padx=40,pady=10,command=lambda: button_click(9))
button_0=Button(root,text='0',padx=40,pady=10,command=lambda: button_click(0))
button_addition=Button(root,text='+',padx=40,pady=10,command=button_add)
button_equal=Button(root,text='=',padx=40,pady=10,command=button_equalto)
button_clear=Button(root,text='clr',padx=40,pady=10,command= button_clear)
button_sub=Button(root,text='-',padx=40,pady=10,command= button_subtract)
button_multiply=Button(root,text='*',padx=40,pady=10,command=button_multiplication)
button_division=Button(root,text='/',padx=40,pady=10,command=button_divide)


#positioning the buttons
button_1.grid(row=3,column=0)
button_2.grid(row=3,column=1)
button_3.grid(row=3,column=2)

button_4.grid(row=2,column=0)
button_5.grid(row=2,column=1)
button_6.grid(row=2,column=2)

button_7.grid(row=1,column=0)
button_8.grid(row=1,column=1)
button_9.grid(row=1,column=2)

button_0.grid(row=4,column=0)
button_addition.grid(row=4,column=1)
button_sub.grid(row=4,column=2)

button_multiply.grid(row=5,column=0)
button_division.grid(row=5,column=1)
button_equal.grid(row=5,column=2)

button_clear.grid(row=6,column=1)

root.mainloop()

And the output ..

If you want to build a Pokedex ..

https://codeddevil-01blogs.blogspot.com/2021/06/pokedex-in-python.html

If you want to build an analog clock ..

https://codeddevil-01blogs.blogspot.com/2021/06/clock-development-part-2-in-python.html