Lecture 12 — Data Types, Variables & Basic Arithmetic⌗

Instructor: Laksh Budhrani

Lecture 12 — Data Types, Variables & Basic Arithmetic⌗

Instructor: Laksh Budhrani

Objectives⌗

1. Learn the basic Python data types
2. Understand how to store different types of data in variables
3. Learn the four basic arithmetic operators
4. Use variables and arithmetic operators to solve simple problems

Objective 1 — Basic Data Types⌗

Simple Definition⌗

A data type tells Python what kind of data a value is.

The four basic data types we will use are:

Examples⌗

age = 16
price = 12.50
name = "John"
is_student = True

In this example:

• age stores an integer
• price stores a float
• name stores a string
• is_student stores a boolean

Objective 2 — Variables⌗

Simple Definition⌗

A variable is a name used to store a value.

age = 16

Here:

• age is the variable
• 16 is the value stored in the variable

We can use the variable later in our program:

age = 16

print(age)
print(age + 1)

Output:

16
17

Variables Can Store Different Data Types⌗

student_name = "Alex"
student_age = 16
student_gpa = 3.5
is_present = True

The value stored in a variable determines its data type.

Objective 3 — Basic Arithmetic Operators⌗

Python can be used as a calculator.

The four basic arithmetic operators are:

Examples⌗

a = 10
b = 5

print(a + b)
print(a - b)
print(a * b)
print(a / b)

Output:

15
5
50
2.0

Order of Operations⌗

Python follows the normal mathematical order of operations.

We can remember this as DMAS:

• D — Division
• M — Multiplication
• A — Addition
• S — Subtraction

For example:

result = 10 + 5 * 2
print(result)

Output:

20

Multiplication happens before addition.

We can use parentheses when we want a calculation to happen first:

result = (10 + 5) * 2
print(result)

Output:

30

Objective 4 — Using Variables for Calculations⌗

Variables can be used in mathematical expressions.

For example:

price = 25
quantity = 4

total = price * quantity

print(total)

Output:

100

We can also use the result of one calculation in another calculation:

length = 10
width = 4

area = length * width
cost = area * 2

print(area)
print(cost)

Output:

40
80

This allows us to solve real-world problems by storing information in variables and using mathematical formulas.

Check Your Knowledge⌗

1. Which data type is used to store a whole number?⌗

• A. float
• B. int
• C. str
• D. bool

2. Which data type is used to store text?⌗

• A. int
• B. float
• C. str
• D. bool

3. What is the value of 10 + 5 * 2?⌗

• A. 30
• B. 25
• C. 20
• D. 15

4. Which operator is used for multiplication in Python?⌗

• A. x
• B. ×
• C. *
• D. %

5. What type of value is stored in price = 12.50?⌗

• A. int
• B. float
• C. str
• D. bool

6. What is the purpose of a variable?⌗

• A. To repeat a program
• B. To store a value
• C. To stop a program
• D. To create a loop

Guided Practice⌗

Question 1 — Rectangle⌗

Write a program that calculates the area and perimeter of a rectangle.

The program should accept the length and width as input.

Question 2 — Circle⌗

Write a program that calculates the diameter, circumference, and area of a circle.

The program should accept the radius as input.

Use $\pi = 3.14159$.

Question 3 — Five Student Scores⌗

Write a program that accepts the scores of five students and calculates their sum, average, and product.

Independent Practice⌗

Question 1 — Temperature Conversion⌗

Write a program that converts a temperature from Fahrenheit to Celsius.

Question 2 — Simple Interest⌗

Write a program that calculates the simple interest and total amount for a given principal, annual interest rate, and number of years.

Question 3 — Shopping Receipt⌗

Write a program that calculates the subtotal, sales tax, and final total for an item.

The program should accept the item price, quantity, and sales tax rate.

Notes⌗

• Use variables to store values.
• Use input() to get information from the user.
• Remember that input() returns a string.
• Use int() or float() when necessary.
• Use +, -, *, and / for basic arithmetic.
• Use parentheses to control the order of operations.
• Use meaningful variable names.

Submission Instructions⌗

Submit your work in Google Classroom by:

1. Creating a Google Doc
2. Pasting your code into the document
3. Adding a screenshot of your output
4. Turning in the Google Doc to the appropriate assignment