Variables, Types & Expressions

Lesson 1 · OKSTEM College · Associate of Science in Computer Science

Variables, Types & Expressions

Python is a dynamically typed language — variables hold references to objects, and the type is determined at runtime.

Core Built-in Types

Type	Example	Notes
int	42, -7, 0	Arbitrary precision
float	3.14, 1e-9	IEEE 754 double
bool	True, False	Subclass of int
str	"hello"	Immutable Unicode
NoneType	None	Absence of value

# Assignment
x = 42
pi = 3.14159
name = "Alice"
is_enrolled = True

# Arithmetic operators
10 + 3   # 13
10 - 3   # 7
10 * 3   # 30
10 / 3   # 3.333... (float division)
10 // 3  # 3       (floor division)
10 % 3   # 1       (modulo / remainder)
2 ** 10  # 1024    (exponentiation)

# Type checking
type(x)        # <class 'int'>
isinstance(x, int)  # True

Python gotcha: Integer division // rounds toward negative infinity: -7 // 2 == -4, not -3.

Lab — Expression Evaluator

a: 7 b: 3

Knowledge Check

What does the // operator do in Python?

What type does Python assign to 3.14?

type(True) in Python returns

Which operator gives the remainder of division?

2 ** 8 evaluates to