Python Tutorials

Choose a lesson to begin

Hello World and Print Statements
Learn the basics of printing output in Python
Beginner
Variables and Data Types
Store and work with different types of data
Beginner
Math and Arithmetic
Perform calculations and mathematical operations
Beginner
F-Strings and Formatting
Format text output with embedded variables
Beginner
String Methods
Transform and manipulate text with built-in methods
Beginner
Lists and For Loops
Store multiple items and iterate through them
Beginner
List Comprehensions and Generator Expressions
Master concise, Pythonic ways to create and transform sequences
Intermediate
Dictionaries and Advanced Data Structures
Master key-value mappings, nested structures, and efficient data organization
Intermediate
Functions, Decorators, and Functional Programming
Write reusable code with functions, decorators, lambda expressions, and functional patterns
Intermediate
Object-Oriented Programming (OOP)
Master classes, objects, inheritance, and OOP design patterns
Advanced
Error Handling and Exceptions
Handle errors gracefully with try-except, custom exceptions, and error recovery
Intermediate
File I/O and Data Persistence
Read and write files, work with JSON/CSV, and persist application data
Advanced

Math and Arithmetic

Python is excellent at math! Let's learn the basic arithmetic operators.

The Basic Operators

Addition (+)

print(5 + 3)      # 8
print(10 + 2.5)   # 12.5

Subtraction (-)

print(10 - 3)     # 7
print(5.5 - 2.5)  # 3.0

Multiplication (*)

print(6 * 7)      # 42
print(3.5 * 2)    # 7.0

Division (/)

print(10 / 2)     # 5.0
print(15 / 4)     # 3.75

Note: Division always returns a decimal (float), even if the result is a whole number!

Using Variables in Math

apples = 10
oranges = 5
total_fruit = apples + oranges
print(total_fruit)  # 15

You can update variables with math:

score = 100
score = score + 10  # add 10 to current score
print(score)  # 110

Order of Operations

Python follows standard math rules (PEMDAS):

  • Parentheses
  • Exponents (not covered yet)
  • Multiplication and Division (left to right)
  • Addition and Subtraction (left to right)

    • result = 2 + 3 * 4
print(result)  # 14 (not 20!)
# 3 * 4 = 12, then 2 + 12 = 14

    Use parentheses to control order:

    result = (2 + 3) * 4
print(result)  # 20
# 2 + 3 = 5, then 5 * 4 = 20

    Negative Numbers

    temperature = -5
print(temperature)
    change = temperature + 10
print(change)  # 5

    Real-World Example: Shopping Cart

    # item prices
shirt = 25.99
pants = 45.00
shoes = 89.99
# calculate subtotal
subtotal = shirt + pants + shoes
print("Subtotal:", subtotal)
# calculate 8% tax
tax = subtotal * 0.08
print("Tax:", tax)
# calculate total
total = subtotal + tax
print("Total:", total)

    Try It Out!

  • Create a tip calculator: meal cost × 0.20 (20% tip)
  • Convert Celsius to Fahrenheit: (celsius × 9/5) + 32
  • Calculate the area of a rectangle: length × width
  • Calculate your age in days: age × 365

    • Common Mistakes

    Forgetting parentheses: 

    # wrong
result = 100 + 50 / 2  # 125.0 not 75! 
# right
result = (100 + 50) / 2  # 75.0

    Dividing by zero: 

    # this will cause an error!
print(10 / 0)

    Next Steps

    Now that you can do math, learn about F-Strings and Formatting to display your results nicely!

    🐍 Python Runner