Written: August 22, 2026
A first calculator is really an if/elif ladder (or match) plus careful division-by-zero handling. Keep the UI in the terminal until the logic is solid.
Working example
a = float(input("First number: "))
op = input("Operator (+ - * /): ").strip()
b = float(input("Second number: "))
if op == "+":
result = a + b
elif op == "-":
result = a - b
elif op == "*":
result = a * b
elif op == "/":
if b == 0:
raise SystemExit("Cannot divide by zero")
result = a / b
else:
raise SystemExit("Unknown operator")
print("Result:", result)Next steps
Wrap the logic in a function and loop until the user types q. That turns a one-shot script into a tiny REPL.
Keep learning
If this walkthrough on python calculator code helped, open the code again and change one input or assumption. Small experiments beat rereading the same example.
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