function calculate(num1,num2,operator) if operator == "+" then return num1 + num2 elseif operator == "-" then return num1 - num2 elseif operator == "*" then return num1 * num2 elseif operator == "/" then if num2 == 0 then return "Error: Division by zero is not allowed." else return num1 / num2 end else return "Error: Invalid operator." end end io.write("Enter the first number: ") local input1 = io.read() local number1 = tonumber(input1) if not number1 then print("Invalid input. Please enter a valid number.") os.exit(1) end io.write("Enter an operator (+, -, *, /): ") local operator = io.read() io.write("Enter the second number: ") local input2 = io.read() local number2 = tonumber(input2) if not number2 then print("Invalid input. Please enter a valid number.") os.exit(1) end local result = calculate(number1, number2, operator) print("Result: " .. tostring(result)) -- nope no flag here, keep looking :P