Altcademy - a Forbes magazine logo Best Coding Bootcamp 2023

What is floor division in Python

Understanding Floor Division

When you first start learning programming, you encounter a variety of mathematical operations that are fundamental to writing code. Among these operations is something called "floor division." But what exactly is floor division, and how does it work in Python?

To put it simply, floor division is a type of division that rounds down the result to the nearest whole number. In Python, floor division is performed using the // operator. It's different from regular division, which uses the / operator and gives you a floating-point number (a number with a decimal point) as the result.

Regular Division vs. Floor Division

Let's take a moment to compare regular division with floor division to get a better sense of the difference.

# Regular division
result_regular = 7 / 2
print(result_regular)  # Output: 3.5

# Floor division
result_floor = 7 // 2
print(result_floor)  # Output: 3

In the example above, when we divide 7 by 2 using regular division, we get 3.5. However, when we use floor division, the result is 3. The floor division operator // has "floored" or rounded down the result to the nearest whole number.

Why "Floor" in Floor Division?

The term "floor" comes from a mathematical function called the "floor function." This function takes a real number (which can have a fractional part) and maps it to the largest integer less than or equal to it. In other words, it chops off the decimal part and gives you the whole number that's just below or equal to the original number.

Imagine you're standing on a staircase, and each step represents a whole number. If you're standing between two steps (say, between 3 and 4), the floor function would place you on step 3, because that's the last full step you're still on.

Floor Division with Negative Numbers

Floor division can be a bit trickier when it comes to negative numbers. Let's see how it works with an example:

# Floor division with negative number
negative_result = -7 // 2
print(negative_result)  # Output: -4

You might have expected the result to be -3, but it's actually -4. This is because the floor division rounds down towards the more negative number, not just towards zero.

The Modulo Operator and Floor Division

Another operator that often goes hand-in-hand with floor division is the modulo operator %. This operator gives you the remainder of a division operation.

# Modulo operation
remainder = 7 % 2
print(remainder)  # Output: 1

The modulo operator can be thought of as telling you how many steps you would have to move up to reach the next whole number on our imaginary staircase. In this case, after dividing 7 by 2, you would have to move up 1 step to get from 3 to 4.

When combined with floor division, the modulo operation can be particularly useful:

# Combination of floor division and modulo
floor_result = 7 // 2
remainder_result = 7 % 2
print("Floor Result:", floor_result)  # Output: 3
print("Remainder:", remainder_result)  # Output: 1

Here, you can see that the number 7 can be broken down into 3 pairs of 2 (which is the floor division result), with 1 left over (which is the modulo result).

Real-world Analogy

To further illustrate floor division, let's use a real-world analogy. Imagine you have a box of cookies, and you want to share them equally among your friends. If there are 7 cookies and 2 friends, you can give each friend 3 cookies, and you'll have 1 cookie left over. The operation of giving each friend 3 cookies is like floor division, and the 1 cookie left over is like the modulo operation.

Practical Uses of Floor Division

Floor division is not just a mathematical curiosity; it has practical uses in programming. Here are a few examples:

  • Indexing: When dealing with lists or arrays, you might need to find the middle index. Floor division can be used to get an integer index.
  • Time calculations: If you're working with time in seconds and need to convert to minutes, floor division can give you the full minutes.
  • Pagination: When implementing pagination (dividing content into separate pages), floor division can help determine the number of full pages.
# Practical example: Time calculation
total_seconds = 123
minutes = total_seconds // 60
seconds = total_seconds % 60
print(f"{minutes} minutes and {seconds} seconds")  # Output: 2 minutes and 3 seconds


Floor division is a fundamental operation in Python that allows you to divide numbers and round down to the nearest whole number. It's like splitting something into equal parts and seeing how many full parts you can make, without considering any leftovers. This operation, represented by the // operator, can be incredibly useful in a variety of programming scenarios, from handling time calculations to managing pagination.

As you continue your journey in learning Python and programming in general, you'll find that understanding and using floor division effectively will help you solve problems more efficiently. Remember, programming is like learning a new language; the more you practice and play with the concepts, the more fluent you become. So go ahead, try out some examples, and see where floor division can take you in your coding adventures!