Today, let's start with the first topic of Python Coding Challenge:

*Variables & Data Types*


*What is a variable?*

Think of a variable as a label on a container that holds some data. You create a variable by giving it a name and putting a value inside.

In Python, it looks like this:

name = Alex
age = 25
height = 5.9
is_student = True

- name holds text (called a string) — notice the quotes!

- age holds a whole number (integer)

- height holds a decimal number (float)

- is_student holds a True/False value (boolean)

You can check a variable’s type using type():

print(type(name)) class 'str'
print(type(age)) class 'int'


*Why use variables?*

They let you store information so your program can remember it and use it later — like a player's score or your name.

*Valid Variable Names*

Python has some rules for naming variables:

✅ Must start with a letter or underscore
✅ Can contain letters, numbers, and underscores
❌ Cannot start with a number
❌ Cannot use Python’s built-in keywords like if, while, class, etc.

*Examples:*

user_name = Amit valid
_user2 = Riya valid
2nd_user = Error! ❌ Invalid: starts with number


*Let’s build a small project!*

We’ll write a simple program that asks for your name, age, and favorite hobby, then prints a fun personalized message.

*Here’s the full code:*

Ask the user for their name and save it in a variable
name = input(What's your name? )

Ask for their age and save it
age = input(How old are you? )

Ask for their favorite hobby and save it
hobby = input(What's your favorite hobby? )

Print a personalized message using the info collected
print(fHey name! So you’re age years old and love hobby. That’s awesome!)

*How this works:*

input() waits for you to type something and press Enter — whatever you type gets saved in the variable.

print() shows a message on the screen.

The f means you can include variables inside the message for personalization.

Now, let’s move on to next topic in the Python coding challenge.

*Operators in Python*

Operators are special symbols or keywords that perform operations on variables and values.

*Types of Operators in Python:*

*1. Arithmetic Operators*

Used for basic math:
+ (add), - (subtract), * (multiply), / (divide), // (floor divide), % (modulus), ** (power)

a = 10
b = 3
print(a + b) 13
print(a ** b) 1000


*2. Comparison Operators*

Used to compare two values:
==, !=, , , =, =

x = 5
print(x == 5) True
print(x != 3) True


*3. Logical Operators*

Used to combine conditional statements:
and, or, not

age = 20
print(age 18 and age 25) True


*4. Assignment Operators*

Used to assign values to variables:
=, +=, -=, *=, /=, etc.

score = 10
score += 5 score is now 15


*Mini Project: Build a Simple Calculator*

Let’s apply what we’ve learned!

*Task: Build a calculator that asks the user to enter two numbers and an operator, then prints the result.*

*Approach*

1. Take two numbers from the user.
2. Ask for an operator (+, -, *, /).
3. Perform the operation based on what the user entered.
4. Print the result, or shows Invalid operator! if the input is wrong.

*Python Code*:

num1 = float(input(Enter first number: ))
op = input(Enter operator (+, -, *, /): )
num2 = float(input(Enter second number: ))

if op == +:
print(num1 + num2)
elif op == -:
print(num1 - num2)
elif op == *:
print(num1 * num2)
elif op == /:
print(num1 / num2)
else:
print(Invalid operator!)

*Variables & Data Types*


*What is a variable?*

Think of a variable as a label on a container that holds some data. You create a variable by giving it a name and putting a value inside.

In Python, it looks like this:

name = Alex
age = 25
height = 5.9
is_student = True

- name holds text (called a string) notice the quotes!

- age holds a whole number (integer)

- height holds a decimal number (float)

- is_student holds a True/False value (boolean)

You can check a variables type using type():

print(type(name)) class 'str'
print(type(age)) class 'int'


*Why use variables?*

They let you store information so your program can remember it and use it later like a player's score or your name.

*Valid Variable Names*

Python has some rules for naming variables:

&9989; Must start with a letter or underscore
&9989; Can contain letters, numbers, and underscores
&10060; Cannot start with a number
&10060; Cannot use Pythons built-in keywords like if, while, class, etc.

*Examples:*

user_name = Amit valid
_user2 = Riya valid
2nd_user = Error! &10060; Invalid: starts with number


*Lets build a small project!*

Well write a simple program that asks for your name, age, and favorite hobby, then prints a fun personalized message.

*Heres the full code:*

Ask the user for their name and save it in a variable
name = input(What's your name? )

Ask for their age and save it
age = input(How old are you? )

Ask for their favorite hobby and save it
hobby = input(What's your favorite hobby? )

Print a personalized message using the info collected
print(fHey name! So youre age years old and love hobby. Thats awesome!)

*How this works:*

input() waits for you to type something and press Enter whatever you type gets saved in the variable.

print() shows a message on the screen.

The f means you can include variables inside the message for personalization.