Python Arithmetic Operators

Arithmetic operators are symbols that tell Python to perform mathematical operations on values.

Python supports all of the common mathematical operations you would expect from a calculator, along with several useful operations specifically designed for programming.

print(10 + 3)
print(10 - 3)
print(10 * 3)
print(10 / 3)
print(10 // 3)
print(10 % 3)
print(2 ** 3)

13
7
30
3.3333333333333335
3
1
8

The plus sign + is used to add two or more numeric values.

first_number = 15
second_number = 8

result = first_number + second_number

print(result)

23

Addition can also be used with floating-point numbers.

price = 19.99
delivery = 4.50

total = price + delivery

print(total)

The minus sign - subtracts one value from another.

balance = 500
expense = 175

remaining = balance - expense

print(remaining)

325

Subtraction can produce negative numbers when the second value is larger than the first.

result = 10 - 25

print(result)

-15

Python uses the asterisk * for multiplication.

price = 250
quantity = 4

total = price * quantity

print(total)

1000

The forward slash / performs division.

total = 100
people = 4

share = total / people

print(share)

25.0

result = 10 / 2

print(result)
print(type(result))

5.0
<class 'float'>

Floor division uses two forward slashes: //.

It divides two numbers and returns the result rounded down to the nearest whole number.

result = 10 // 3

print(result)

3

Compare this with normal division:

print(10 / 3)
print(10 // 3)

3.3333333333333335
3

The modulus operator % returns the remainder after division.

result = 10 % 3

print(result)

1

Why is the answer 1?

Three fits into ten three complete times:

3 × 3 = 9
10 - 9 = 1

Therefore, the remainder is 1.

number = 20

print(number % 2)

0

If a number divided by 2 leaves a remainder of 0, the number is even.

Python uses two asterisks ** to calculate powers.

result = 2 ** 3

print(result)

8

This means:

2 ** 3

# Same as:
# 2 × 2 × 2

You can also calculate squares and cubes.

number = 5

square = number ** 2
cube = number ** 3

print(square)
print(cube)

25
125

When an expression contains multiple operators, Python needs to know which operation should be performed first.

This order is called operator precedence.

Python generally follows this order for arithmetic:

1. Parentheses ()
2. Exponentiation **
3. Multiplication, division, floor division, and modulus
4. Addition and subtraction

result = 2 + 3 * 4

print(result)

14

Python performs multiplication before addition:

2 + 3 * 4

# First:
3 * 4 = 12

# Then:
2 + 12 = 14

Parentheses allow you to explicitly control which operation Python performs first.

result = 2 + 3 * 4

print(result)

14

result = (2 + 3) * 4

print(result)

20

Arithmetic becomes much more useful when values are stored in variables.

length = 12
width = 5

area = length * width

print(area)

60

You can combine several arithmetic operations in a single expression.

price = 1000
discount = 100
tax = 50

final_price = price - discount + tax

print(final_price)

950

You can combine arithmetic operators with input() to build interactive programs.

Remember that input() returns text, so numeric input should normally be converted before performing calculations.

first = float(input("Enter first number: "))
second = float(input("Enter second number: "))

total = first + second

print("Total:", total)

Enter first number: 25
Enter second number: 15
Total: 40.0

age = int(input("Enter your age: "))

next_year = age + 1

print("Next year:", next_year)

Shopping Bill

Arithmetic operators can calculate the total price of products.

item_price = 1200
quantity = 3

subtotal = item_price * quantity

print("Subtotal:", subtotal)

Subtotal: 3600

Rectangle Area

length = 20
width = 8

area = length * width

print("Area:", area)

Area: 160

Average of Numbers

math_marks = 80
english_marks = 75
computer_marks = 90

total = math_marks + english_marks + computer_marks

average = total / 3

print("Total:", total)
print("Average:", average)

Total: 245
Average: 81.66666666666667

1. Using the wrong division operator

Remember the difference:

print(7 / 2)
print(7 // 2)

3.5
3

2. Forgetting operator precedence

This:

result = 10 + 5 * 2

produces 20, not 30, because multiplication happens first.

3. Forgetting to convert input

Input values are strings by default.

number = int(input("Enter a number: "))

result = number * 2

print(result)

4. Dividing by zero

Python cannot divide a number by zero.

result = 10 / 0

Try these exercises yourself before looking at other solutions.

Build a small Python program that asks the user for the price of a product and the quantity purchased.

Your program should calculate:

• Subtotal
• 10% discount
• Final price after discount

price = float(input("Enter product price: "))
quantity = int(input("Enter quantity: "))

subtotal = price * quantity
discount = subtotal * 0.10
final_price = subtotal - discount

print("Subtotal:", subtotal)
print("Discount:", discount)
print("Final price:", final_price)

Arithmetic operators are fundamental building blocks of Python programming. They allow programs to perform calculations, process data, and solve real-world problems.