Walkthrough: First Steps¶

This guide walks through the thinking process for this exercise. It does NOT give you the complete solution. For that, see SOLUTION.md.

Before reading this¶

Try the exercise yourself first. Spend at least 10 minutes. If you have not tried yet, close this file and open the exercise file.

Understanding the problem¶

You need to open Python in interactive mode (the >>> prompt) and type simple commands. This is not about writing a program yet -- it is about seeing that Python responds to what you type.

Think of it like a conversation: you type something, Python answers.

Planning before code¶

There are only two things to do:

Open Python in your terminal so you see the >>> prompt
Type commands and watch what Python gives back

Step 1: Get into interactive mode¶

Open your terminal (Command Prompt on Windows, Terminal on Mac/Linux) and type:

python

You should see something like:

Python 3.12.0
>>>

That >>> is Python waiting for you. If you see it, you are in.

What if it does not work?¶

On some systems you need python3 instead of python
If you get "command not found", Python is not installed yet -- go back to the setup guide

Step 2: Try math¶

Type this and press Enter:

2 + 2

Python should answer 4. That is it. You just made a computer do math.

Predict before you scroll¶

What do you think 5 * 6 will give you? What about 100 / 4? Think about it, then try each one.

Step 3: Try printing text¶

Type this:

print("Hello, I am learning Python!")

Python prints your message back. The print() function is how you tell Python to display something.

Step 4: Leave interactive mode¶

When you are done experimenting, type:

exit()

Step 5: Run the exercise file¶

Now try running the file itself:

python exercise.py

This runs all the commands in the file at once instead of one at a time.

Common mistakes¶

Mistake	Why it happens	How to fix
`python` shows "not found"	Python is not installed or not in your PATH	Reinstall Python and check "Add to PATH"
Typing `python exercise.py` inside `>>>`	You are already in Python -- this command is for the terminal	Type `exit()` first to get back to the terminal
Forgetting quotes around text	Python treats unquoted words as variable names	Always put text in quotes: `"like this"`

What to explore next¶

Try calculating your age in days: your_age * 365
Try exponents with **: what is 2 ** 10?