Arithmetic Operators in Python


TL ; DR:

  • We can tell computers to perform calculations for us using +, -, *, /:

    print(2 + 6) # Prints 8
    print(10 - 7) # Prints 3
    print(3 * 3) # Prints 9
    print(6 / 2) # Prints 3
    


  • We can also use variables. In these examples, Python will replace variable num with its value 6 to do the calculations:

    num = 6
    print(num + 5) # Prints 11
    print(10 - num) # Prints 4
    print(3 * num) # Prints 18
    print(num / 2) # Prints 3
    





Full lesson:

Computers absolutely excel at performing calculations. The "compute" in their name comes from their historical association with providing answers to mathematical questions.

We've learned that in Python there are two types of numbers: integers, which are whole numbers like 10, and floating point numbers or floats, which are numbers with a decimal point like 3.145.


Arithmetic operators

Arithmetic operators are used with numeric values to perform common mathematical operations:

Operator Name Examples
+ Addition 3 + 5,  x + 5,  3 + y,  x + y
- Subtraction 8 - 3,  8 - y,  x - 3,  x - y
* Multiplication 3 * 5,  3 * y,  x * 5,  x * y
/ Division 8 / 4,  8 / y,  x / 8,  x / y
% Modulus 8 % 4,   8 % y,  x % 4,  x % y
** Exponentiation 3 ** 2,  3 ** y,   x ** 3,  x ** y
// Floor division 8 // 4,  8 // y,  x // 8,  x // y


Note that performing arithmetic on variables does not change the variable - you can only update a variable using the = sign.

Let's go through some examples together to better understand how each operator works:


Addition

# Declare 2 variables and initialize them:
a = 2
b = 3

print(a + b) # Output: 5

print(a + 10) # Output: 12

Subtraction

# Declare 2 variables and initialize them:
a = 2
b = 3

print(a - b) # Output: -1

print(10 - b) # Output: 7

Multiplication

# Declare 2 variables and initialize them:
a = 2
b = 3

print(a * 5) # Output: 10

print(-2 * a * b) # Output: -12

Division

# Declare 2 variables and initialize them:
a = 2
b = 3

print(b / a) # Output: 1.5

print(a / 10) # Output: 0.2

Exponentiation

The ** operator performs the exponential calculation (2**3 translates to 2 * 2 * 2):

# Declare 2 variables and initialize them:
a = 2
b = 3

print(2 ** 3) # Output: 8

print(b ** a) # Output: 9

We left the modulo (%) and floor division (//) operators for the next lesson.


Assignment
Follow the Coding Tutorial and let's practice with arithmetic operators!


Hint
Look at the examples above if you get stuck.


Introduction

In this lesson, we will explore arithmetic operators in Python. Arithmetic operators are fundamental in programming as they allow us to perform basic mathematical operations. These operators are essential for tasks ranging from simple calculations to complex algorithms. Understanding how to use arithmetic operators is crucial for any programmer, as they are used in a wide variety of scenarios, such as data analysis, game development, and financial calculations.

Understanding the Basics

Before diving into the details, let's understand the basic arithmetic operators available in Python:

These operators can be used with both integers and floating-point numbers. Let's look at some simple examples to illustrate these concepts:

print(2 + 3)  # Output: 5
print(5 - 2)  # Output: 3
print(4 * 3)  # Output: 12
print(8 / 2)  # Output: 4.0
print(7 % 3)  # Output: 1
print(2 ** 3) # Output: 8
print(9 // 2) # Output: 4

Main Concepts

Let's delve deeper into each arithmetic operator and understand how they work with variables:

Addition

a = 2
b = 3
print(a + b)  # Output: 5
print(a + 10) # Output: 12

Subtraction

a = 2
b = 3
print(a - b)  # Output: -1
print(10 - b) # Output: 7

Multiplication

a = 2
b = 3
print(a * 5)  # Output: 10
print(-2 * a * b) # Output: -12

Division

a = 2
b = 3
print(b / a)  # Output: 1.5
print(a / 10) # Output: 0.2

Exponentiation

a = 2
b = 3
print(2 ** 3) # Output: 8
print(b ** a) # Output: 9

Examples and Use Cases

Let's explore some real-world use cases where arithmetic operators are beneficial:

Calculating Total Price

price_per_item = 20
quantity = 5
total_price = price_per_item * quantity
print(total_price)  # Output: 100

Converting Temperature

celsius = 25
fahrenheit = (celsius * 9/5) + 32
print(fahrenheit)  # Output: 77.0

Finding Remainder

total_candies = 29
candies_per_child = 4
remainder = total_candies % candies_per_child
print(remainder)  # Output: 1

Common Pitfalls and Best Practices

When working with arithmetic operators, it's important to be aware of common pitfalls and follow best practices:

Advanced Techniques

Once you are comfortable with basic arithmetic operators, you can explore advanced techniques such as:

Code Implementation

Here are some well-commented code snippets demonstrating the correct use of arithmetic operators:

# Calculate the area of a rectangle
length = 5
width = 3
area = length * width
print(area)  # Output: 15

# Calculate the average of three numbers
num1 = 10
num2 = 20
num3 = 30
average = (num1 + num2 + num3) / 3
print(average)  # Output: 20.0

Debugging and Testing

When working with arithmetic operations, debugging and testing are crucial:

import unittest

def add(a, b):
    return a + b

class TestMathOperations(unittest.TestCase):
    def test_add(self):
        self.assertEqual(add(2, 3), 5)
        self.assertEqual(add(-1, 1), 0)

if __name__ == '__main__':
    unittest.main()

Thinking and Problem-Solving Tips

Here are some strategies for approaching problems related to arithmetic operations:

Conclusion

In this lesson, we covered the fundamental arithmetic operators in Python. Mastering these operators is essential for any programmer, as they are used in a wide range of applications. By understanding and practicing these concepts, you will be well-equipped to handle various mathematical operations in your code.

Additional Resources

For further reading and practice, check out the following resources: