Simple Calculator in Python

# Simple Calculator in Python

def add(x, y):
    return x + y

def subtract(x, y):
    return x - y

def multiply(x, y):
    return x * y

def divide(x, y):
    if y == 0:
        return "Error! Division by zero."
    return x / y

print("Select operation:")
print("1. Add")
print("2. Subtract")
print("3. Multiply")
print("4. Divide")

while True:
    choice = input("Enter choice (1/2/3/4): ")

    if choice in ('1', '2', '3', '4'):
        num1 = float(input("Enter first number: "))
        num2 = float(input("Enter second number: "))

        if choice == '1':
            print(f"Result: {add(num1, num2)}")
        elif choice == '2':
            print(f"Result: {subtract(num1, num2)}")
        elif choice == '3':
            print(f"Result: {multiply(num1, num2)}")
        elif choice == '4':
            print(f"Result: {divide(num1, num2)}")
    else:
        print("Invalid input")

    next_calculation = input("Do you want to perform another calculation? (yes/no): ")
    if next_calculation.lower() != "yes":
        break

print("Goodbye!")

✅ How to run it:

1. Save it as calculator.py
2. Run it in your terminal:

python calculator.py

With a GUI

import tkinter as tk

def click(event):
    text = event.widget.cget("text")
    if text == "=":
        try:
            result = eval(screen.get())
            screen_var.set(result)
        except Exception as e:
            screen_var.set("Error")
    elif text == "C":
        screen_var.set("")
    else:
        screen_var.set(screen_var.get() + text)

root = tk.Tk()
root.title("Calculator")
root.geometry("300x400")

screen_var = tk.StringVar()
screen = tk.Entry(root, textvar=screen_var, font="lucida 20 bold")
screen.pack(fill="x", ipadx=8, pady=10, padx=10)

button_texts = [
    ["7", "8", "9", "/"],
    ["4", "5", "6", "*"],
    ["1", "2", "3", "-"],
    ["0", ".", "=", "+"],
    ["C"]
]

for row in button_texts:
    frame = tk.Frame(root)
    frame.pack()
    for btn_text in row:
        button = tk.Button(frame, text=btn_text, font="lucida 15 bold", padx=20, pady=20)
        button.pack(side="left", padx=5, pady=5)
        button.bind("<Button-1>", click)

root.mainloop()

✅ How to run it:

1. Save it as calculator_gui.py
2. Run:

python calculator_gui.py