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Week 2: Numbers, Math, Text, Loops & User Input

Why Learn This?

Week 2 expands your Python toolkit with the most used language features in real-world programming:

  • Perform calculations and manipulate text.
  • Add interactivity through user input.
  • Automate repetitive tasks with loops.
  • Write conditional logic to build smarter programs.

These skills are foundational for every Python role — from scripting to data science and web development.

Concepts & Notes

Numbers & Math

# Integers and Floats
x = 10      # int
y = 3.5     # float

# Arithmetic Operators
add = x + y
subtract = x - y
multiply = x * y
divide = x / y
floor_div = x // 3
modulus = x % 3
exponent = x ** 2

Strings & Text

# Concatenation
first = "Hello"
second = "World"
greeting = first + " " + second

# String Indexing
word = "Python"
print(word[0])   # P
print(word[-1])  # n

# Slicing
print(word[0:2])   # Py
print(word[2:])    # thon

# Methods
text = "hello"
print(text.upper())    # HELLO
print(text.capitalize())  # Hello
print(text.replace("l", "y"))  # heyyo

Conditionals

# Booleans & Comparisons
a = 5
b = 10
print(a > b)   # False

# if / elif / else
if a > b:
    print("A is greater")
elif a == b:
    print("Equal")
else:
    print("B is greater")

Loops

# for loop
for i in range(5):
    print("Iteration:", i)

# while loop
x = 0
while x < 3:
    print("x is", x)
    x += 1

User Input

# Input always returns a string
name = input("What is your name? ")
print("Hi", name)

# Convert string to int
age = int(input("Enter your age: "))
print("Next year you will be", age + 1)

Modules and Automation

import random

 # A random number between 0 and 10
print(random.randint(0, 10))
# Import pathlib
import pathlib

# Find the path to my Desktop
desktop = pathlib.Path('/Users/martin/Desktop')
# Create a new folder
new_path = pathlib.Path('/Users/martin/Desktop/screenshots')
new_path.mkdir(exist_ok=True)

for filepath in desktop.iterdir():
    # Filter for screenshots only
    if filepath.suffix == '.png':
        # Create a new path for each file
        new_filepath = new_path.joinpath(filepath.name)
        # Move the screenshot there
        filepath.replace(new_filepath)

Quiz – Week 2

  1. What data type does input() return?

  2. What is the result of 3 ** 2?

  3. What does print("hello"[1]) output?

  4. What will this code print?

    x = 10
if x > 5:
    print("High")
else:
    print("Low")

  5. How many times will this loop run?

    for i in range(3):
    print(i)

  6. True or False: while loops must always have a break statement.

Coding Challenges – Week 2

Challenge 1: Greet the User

Instructions: Ask the user for their name and print a greeting message.

Learning Objective: Practice using input() and string concatenation.

# TODO: Ask the user for their name and print a greeting message.

Challenge 2: Simple Calculator

Instructions: Ask the user to input two numbers. Add them and display the result.

Learning Objective: Practice input conversion (int() or float()) and arithmetic operations.

# TODO: Ask the user to input two numbers. Add them and display the result.

Challenge 3: Check Even or Odd

Instructions: Ask the user for a number and tell them whether it is even or odd.

Learning Objective: Use modulus operator % and conditional statements.

# TODO: Ask the user for a number and tell them whether it is even or odd.

Challenge 4: Word Reverser

Instructions: Ask the user to input a word, then print the word reversed.

Learning Objective: Use string slicing to manipulate text.

# TODO: Ask the user to input a word, then print the word reversed.

Challenge 5: Print All Characters of a String

Instructions: Ask for a string and print each character on a new line using a for loop.

Learning Objective: Loop through a string and practice iteration.

# TODO: Ask for a string and print each character on a new line using a `for` loop.

Challenge 6: Countdown Timer

Instructions: Ask the user for a number and count down to zero using a while loop.

Learning Objective: Practice using while loops and decrementing values.

# TODO: Ask the user for a number and count down to zero using a `while` loop.

Week 2 Summary

  • You learned how to work with numbers and math operations in Python.
  • You practiced manipulating text and using string methods and slicing.
  • You used conditionals to make decisions in your programs.
  • You wrote for and while loops to perform repeated tasks.
  • You added interactivity with user input and type conversion.

You're now equipped to build basic interactive programs. These tools will be critical for data processing, logic handling, and user engagement.

For Next Week

Reading

  • https://codingnomads.com/course/python-programming-101
    • Section 7) Numbers and Math
    • Section 8) Text and Strings
    • Section 9) Operators and Booleans
    • Section 10) Conditionals and Loops
    • Section 11) User Input and String Formatting
    • Section 12) Modules and Automation (stretch)

Assignments (in VSCode)

Complete the following exercises -- you can, of course, do them all:

  • 08_numbers-and-math
    • 08_03_seconds_years.py
    • 08_07_convert.py
  • 09_strings-and-text
    • 09_01_longest.py
    • 09_02_big_python.py
    • 09_04_sentence_pieces.py
    • 09_08_edibles.py
    • 09_10_file_extensions.py
  • 10_operators-and-booleans
    • 10_01_shorthands.py
    • 10_03_temp_converter.py
    • 10_04_modulo_magic.py
    • 10_07_logic_and_booleans.py
  • 11_conditionals-and-loops
    • 11_01_decypher_cipher.py
    • 11_04_hunger_meter.py
    • 11_05_squares.py
    • 11_09_primes.py (challenging!)
    • 11_11_fizzbuzz.py
    • 11_13_pig_latinization.py
  • 12_user-input-string-formatting
    • 12_01_input_occurrence.py
    • 12_02_input_replace.py
    • 12_06_vowel_counter.py
  • 13_modules-and-automation
    • 13_01_math_pi.py
    • 13_02_the_time_please.py
    • 13_03_tech_support_bliss.py