Python Basics – Part 2: Operators in Python

As part of my 5-week Python training course, these notes cover the most important Python operators — from arithmetic and string operations to logical and comparison operators.
We’ll also look at assignment shortcuts, the versatile in operator, and chained comparisons.
In upcoming posts, I’ll share extra exercise examples to practice these concepts.

Arithmetic Operators

Python supports standard mathematical operations: addition (+), subtraction (-), multiplication (*), and division (/).

print(3 + 4)
print(10 - 7)
print(12 * 2)

Output:

7
3
24

You can also store results in a variable:

result = 3 + 4
print(result)

Output:

7

Division (/)

In Python 3, division with / always returns a float.

print(9 / 3)        # 3.0
print(10 / 3)       # 3.3333333333333335
print(round(10/3,2))  # 3.33

Floor Division (//)

Performs division and rounds down to the nearest integer.

print(9 // 3)   # 3
print(10 // 3)  # 3

Modulo (%)

Returns the remainder of a division.

print(10 % 3)  # 1
print(7 % 3)   # 1
print(4 % 3)   # 1

Common use: checking if a number is even or odd.

num = 7
print(num % 2)  # 1 → odd
num2 = 8
print(num2 % 2) # 0 → even

Special cases:

print(7 % 7)  # 0  (equal numbers)
print(4 % 7)  # 4  (first smaller than second)

Exponentiation (**)

Raises a number to a power.

print(2 ** 3)   # 8
print(2 ** 8)   # 256  (8 bits = 1 byte)
print(2 ** 24)  # 16777216
print(2 ** 32)  # 4294967296  (IPv4 address count)

String Operators

first_name = 'Peter'
last_name = 'Wellert'

Concatenation (+)

Joins strings together. Both operands must be strings.

name = first_name + last_name
print(name)

name2 = first_name + ' ' + last_name
print(name2)

Output:

PeterWellert
Peter Wellert

If you try to concatenate a string and an integer, Python will throw an error.
To fix this, convert the number using str():

# print('Age: ' + 5)   # ❌ Error
print('Age: ' + str(5))  # ✅ "Age: 5"

String Multiplication (*)

Repeats a string a given number of times.

print('Hello' * 7)

Output:

HelloHelloHelloHelloHelloHelloHello

You can use it for simple separators too:

print('-' * 30)

Comparison Operators

Comparison (or relational) operators always evaluate to a Boolean (True or False).

print(7 == 8)   # False

a = 7
b = 8
answer = a == b
print(answer)

Output:

False

Common Operators

Operator	Meaning	Example	Result
==	Equal to	7 == 7	True
!=	Not equal to	7 != 8	True
>	Greater than	10 > 5	True
<	Less than	3 < 1	False
>=	Greater or equal	5 >= 5	True
<=	Less or equal	4 <= 6	True

Remember: = is assignment, == is comparison.

🧾 Assignment Operators

Assign or update variable values.

number = 42
print(number)

Output:

42

Short Forms

Without shorthand:

x = 23
x = x + 1
print(x)

With shorthand:

x += 6
print(x)

Output:

24
30

Other assignment operators:

x -= 1
x *= 2
x /= 4
x %= 5
x **= 2
print(x)

Multiple Assignment

a = b = c = 0
print(a, b, c)

Output:

0 0 0

Logical Operators

Also called Boolean operators, named after mathematician George Boole.

and

Returns True only if both operands are True.

print(True  and True)   # True
print(True  and False)  # False
print(False and True)   # False
print(False and False)  # False

or

Returns True if at least one operand is True.

print(True  or True)   # True
print(True  or False)  # True
print(False or True)   # True
print(False or False)  # False

not

Negates the Boolean value.

print(not False) # True
print(not True)  # False

num = 7
print(not (num == 8)) # True
print(num != 8)       # True

Membership Operators (in, not in)

Check whether a value exists within a sequence (like a list, string, or tuple).

numbers = [1, 4, 7, 9]
print(4 in numbers)     # True
print(5 in numbers)     # False
print(4 not in numbers) # False
print(5 not in numbers) # True

Equivalent:

print(not (4 in numbers))  # False

Strings:

print('e' in 'Hello')     # True
print('Hell' in 'Hello')  # True

Dictionary keys:

my_dict = {"a": 1, "b": 2}
print("a" in my_dict)  # True
print(1 in my_dict)    # False

Using in as a cleaner alternative to multiple or checks:

num = 8
print(num == 7 or num == 8 or num == 9)  # True
print(num in [7, 8, 9])                  # True

Chained Comparison

Python allows chaining comparisons in a single statement.

num = 7

if 3 < num < 9:
    print("num is between 3 and 9")

Output:

num is between 3 and 9

This is equivalent to:

if num > 3 and num < 9:

but shorter and cleaner.

Summary

In this lesson, we learned:

• Arithmetic operators (+, -, *, /, //, %, **)
• String operators (+, *)
• Comparison and assignment operators
• Logical operators (and, or, not)
• Membership operator (in, not in)
• Chained comparisons

Next up: Conditional Statements and Loops in Python — the foundation for building logic and control flow.