Solution: 01-first-steps¶

STOP — Have you attempted this project yourself first?

Learning happens in the struggle, not in reading answers. Spend at least 20 minutes trying before reading this solution. If you are stuck, try the Walkthrough first — it guides your thinking without giving away the answer.

Complete solution¶

This exercise is done in Python's interactive mode (the >>> prompt), not by writing a file. Here is what you should have typed and seen:

# Step 1: Open your terminal and type "python" to start interactive mode.
# You should see the >>> prompt.

# Step 2: Try basic math.
2 + 2          # WHY: This tests that Python is working — it should respond with 4
10 - 3         # WHY: Subtraction works with the minus sign, just like on paper
5 * 6          # WHY: The * symbol means multiply (the x key is used for variable names)
100 / 4        # WHY: The / symbol means divide — Python gives you 25.0 (a decimal number)

# Step 3: Print a message.
print("Hello, I am learning Python!")  # WHY: print() displays text on screen — the quotes mark where the text starts and ends

# Step 4: Exit interactive mode.
exit()         # WHY: This tells Python you are done — it closes the interactive session

If you ran the exercise.py file directly, here is what it does:

print("If you can see this, you successfully ran a Python file!")  # WHY: Confirms the file ran — if you see this, Python found and executed the file
print()                                                            # WHY: Prints a blank line to add visual spacing between sections
print("Here is some math Python can do:")                          # WHY: Labels the section so you know what comes next
print("2 + 2 =", 2 + 2)      # WHY: Python calculates 2+2 and prints the label and result together
print("10 - 3 =", 10 - 3)    # WHY: Shows subtraction — the comma between items adds a space automatically
print("5 * 6 =", 5 * 6)      # WHY: Shows multiplication — * is the multiply symbol in programming
print("100 / 4 =", 100 / 4)  # WHY: Shows division — notice the result is 25.0 (decimal), not 25
print()                        # WHY: Another blank line for visual breathing room
print("You are off to a great start.")  # WHY: Encouragement — learning to code is a big step

Design decisions¶

Decision	Why	Alternative considered
Use interactive mode first	Seeing instant results builds confidence — you type something, Python responds immediately	Could have started with writing a file, but that adds extra steps before seeing results
Show math before text	Numbers are familiar to everyone — math gives instant proof that Python works	Could have started with print(), but math is more concrete and universal
Use `*` for multiply and `/` for divide	These are the standard symbols in all programming languages — your keyboard does not have a x or / key for math	None — this is universal across programming
Include `exit()` instruction	New users often get stuck in interactive mode, not knowing how to get back to their terminal	Could use Ctrl+D (Mac/Linux) or Ctrl+Z (Windows), but exit() works everywhere

Alternative approaches¶

Approach B: Run the file directly instead of using interactive mode¶

# Save this in a file called first_steps.py and run it with: python first_steps.py
print(2 + 2)          # WHY: Same math, but written in a file instead of typed interactively
print(10 - 3)         # WHY: Every line runs automatically, top to bottom
print(5 * 6)          # WHY: You do not have to wait for each result — they all print at once
print(100 / 4)        # WHY: This is how you will write most Python code going forward
print("Hello, I am learning Python!")  # WHY: Files let you save and re-run your code

Trade-off: Running a file is how you will work most of the time, but interactive mode is better for experimenting because you see each result immediately. Interactive mode is like a calculator; a file is like a recipe.

What could go wrong¶

Scenario	What happens	Prevention
Typing `python` and getting "command not found"	Python is not installed, or your terminal cannot find it	Revisit the setup guide (03_SETUP_ALL_PLATFORMS.md) and make sure Python is on your PATH
Seeing `>>>` but not knowing what to do	You are in interactive mode — Python is waiting for you to type something	Type any math like `2 + 2` and press Enter. Type `exit()` to leave
Forgetting the quotes around text in print()	You get a `NameError` because Python thinks the words are variable names, not text	Always wrap text in quotes: `print("Hello")` not `print(Hello)`
Typing `print "Hello"` without parentheses	You get a `SyntaxError` — Python 3 requires parentheses around print	Always use `print("Hello")` with parentheses
Pressing Enter after `python exercise.py` and nothing happens	You might be in the wrong folder — your terminal cannot find the file	Use `cd` to navigate to the folder containing exercise.py first

Key takeaways¶

Python's interactive mode (>>>) is your playground — use it to experiment, test ideas, and see instant results. You will use it throughout your learning.
Python does math with symbols you mostly know — + for add, - for subtract, * for multiply (not x), / for divide.
print() is how you make Python talk to you — everything you want to display on screen goes inside print(). This is the foundation of every program you will write from here on.