Python follows the PEMDAS rule when deciding the order of operations.
To indicate to Python that a line is comment (and not Python code), you need to write a pound sign (#) as the very first character.
Variables rule They can’t have spaces (e.g., test var is not allowed)
They can only include letters, numbers, and
underscores (e.g., test_var! is not allowed)
They have to start with a letter or underscore (e.g., 1_var is not allowed)
When you see NameError like this, it’s an indication that you should check how you have spelled the variable that it references as “not defined”. Then, to fix the error, you need only correct the spelling.