Lesson 10: Python Refresher — Variables and Data Types

In Python, a variable is like a labeled box that stores a value (such as a number or text). You can name these variables to keep track of data. For example, score = 85 stores the number 85 in a variable called score. Python is dynamically typed, meaning you don't declare variable types explicitly; the type (integer, string, etc.) is determined by the value you assign.

Common data types in Python include:

• Integer (int): Whole numbers, e.g. n = 42.
• Float: Decimal numbers, e.g. price = 17.50.
• String (str): Text enclosed in quotes, e.g. name = "Juan".
• Boolean (bool): True or False values, e.g. is_raining = False.

Understanding types is important because you can only perform certain operations on certain types. For example, 5 + 3 gives 8, but "5" + "3" (string addition) gives "53" (concatenation).

Operators let us do calculations or comparisons. Key operator types:

• Arithmetic operators: +, -, *, /, % (modulo), ** (power). Example: 3 * 4 results in 12.
• Relational (comparison) operators: ==, !=, <, >, <=, >=. These produce Boolean results. Example: 5 > 3 is True.
• Logical operators: and, or, not (combine Boolean conditions). Example: True and False is False.

An expression is a combination of variables, literals, and operators that evaluates to a value. For instance, total = price * quantity uses the arithmetic * operator. Remember operator precedence (multiplication before addition) when writing expressions, or use parentheses to make your intent clear: (a + b) * c.