import math

── Two-operand operations ──────────────────────────────────────────────────

def add(a, b): return a + b def subtract(a, b): return a - b def multiply(a, b): return a * b

def divide(a, b): if b == 0: raise ValueError("Cannot divide by zero.") return a / b

def floor_divide(a, b): if b == 0: raise ValueError("Cannot divide by zero.") return a // b

def modulo(a, b): if b == 0: raise ValueError("Cannot mod by zero.") return a % b

def power(a, b): return a ** b

def log_base(a, b): if a <= 0: raise ValueError("Logarithm argument must be positive.") if b <= 0 or b == 1: raise ValueError("Logarithm base must be > 0 and not 1.") return math.log(a, b)

── Single-operand operations ───────────────────────────────────────────────

def square_root(a): if a < 0: raise ValueError("Cannot take square root of a negative number.") return math.sqrt(a)

def cube_root(a): return math.copysign(abs(a) ** (1 / 3), a)

def absolute(a): return abs(a)

def factorial(a): if a < 0 or a != int(a): raise ValueError("Factorial is only defined for non-negative integers.") return math.factorial(int(a))

def sine(a): return math.sin(math.radians(a)) def cosine(a): return math.cos(math.radians(a))

def tangent(a): if math.cos(math.radians(a)) == 0: raise ValueError("tan is undefined at this angle.") return math.tan(math.radians(a))

def natural_log(a): if a <= 0: raise ValueError("Logarithm argument must be positive.") return math.log(a)

def log10(a): if a <= 0: raise ValueError("Logarithm argument must be positive.") return math.log10(a)

── Helpers ─────────────────────────────────────────────────────────────────

def get_number(prompt): while True: try: return float(input(prompt)) except ValueError: print(" Invalid input. Please enter a number.")

TWO_OP = { "1": ("+", "Addition", add), "2": ("-", "Subtraction", subtract), "3": ("*", "Multiplication", multiply), "4": ("/", "Division", divide), "5": ("//", "Floor Division", floor_divide), "6": ("%", "Modulo", modulo), "7": ("^", "Power", power), "8": ("log_b", "Logarithm (base b)", log_base), }

ONE_OP = { "9": ("√", "Square Root", square_root), "10": ("∛", "Cube Root", cube_root), "11": ("|x|", "Absolute Value", absolute), "12": ("n!", "Factorial", factorial), "13": ("sin", "Sine (degrees)", sine), "14": ("cos", "Cosine (degrees)", cosine), "15": ("tan", "Tangent (degrees)", tangent), "16": ("ln", "Natural Log", natural_log), "17": ("log10", "Log base 10", log10), }

QUIT_KEY = "0"

── Main loop ───────────────────────────────────────────────────────────────

def calculator(): print("\n" + "=" * 40) print(" Python Calculator") print("=" * 40)

while True:
    print("\n── Two-operand operations ──")
    for key, (symbol, label, _) in TWO_OP.items():
        print(f"  {key:>2}. {symbol:<8} {label}")

    print("\n── Single-operand operations ──")
    for key, (symbol, label, _) in ONE_OP.items():
        print(f"  {key:>2}. {symbol:<8} {label}")

    print(f"\n   {QUIT_KEY}. Quit")

    all_keys = list(TWO_OP) + list(ONE_OP) + [QUIT_KEY]
    choice = input("\nSelect an operation: ").strip()

    if choice == QUIT_KEY:
        print("Goodbye!")
        break

    if choice not in all_keys:
        print("  Invalid choice.")
        continue

    try:
        if choice in TWO_OP:
            symbol, label, func = TWO_OP[choice]
            a = get_number("Enter first number:  ")
            b = get_number("Enter second number: ")
            result = func(a, b)
            print(f"\n  {a} {symbol} {b} = {result}")
        else:
            symbol, label, func = ONE_OP[choice]
            a = get_number("Enter number: ")
            result = func(a)
            print(f"\n  {symbol}({a}) = {result}")
    except ValueError as e:
        print(f"  Error: {e}")

if name == "main": calculator()