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What is integer division in Python

Understanding Integer Division

When you were in school, you likely learned about division, the process of determining how many times one number is contained within another. In programming, and specifically in Python, division comes in a couple of different flavors. One of these is integer division, which might not behave as you initially expect if you're coming from a purely mathematical background.

What is Integer Division?

Integer division, often referred to as "floor division," is a type of division that discards the remainder, or fractional part, and only returns the whole number part of the quotient. In Python, we use the // operator to perform integer division.

Imagine you have a pizza cut into 8 slices and you want to share it equally among 3 friends. In normal arithmetic, you would say each person gets 2.66 slices. However, you can't really give someone 0.66 of a slice in real life. Instead, you would give each person 2 slices and you'd have 2 slices left over. Integer division is like sharing pizza slices. It only deals with whole pieces, not fractions.

How Does Integer Division Work in Python?

Let's look at some simple code examples to see integer division in action:

# Integer division of 10 by 3
result = 10 // 3
print(result)  # Output: 3

In the example above, 10 divided by 3 gives us 3.33, but since we're using integer division, we only get the integer part, which is 3.

Here's another example:

# Integer division of -10 by 3
result = -10 // 3
print(result)  # Output: -4

This might seem odd at first. You might expect the result to be -3 since -10 divided by 3 is approximately -3.33. However, Python's integer division always rounds down towards minus infinity. This means that it will round to the lower number, -4 in this case.

The Difference Between Integer Division and Regular Division

In Python, regular division is done using the / operator and it returns a floating-point number (a number with a decimal point). Here's a comparison:

# Regular division
regular_division_result = 10 / 3
print(regular_division_result)  # Output: 3.3333333333333335

# Integer division
integer_division_result = 10 // 3
print(integer_division_result)  # Output: 3

Regular division would give you the exact quotient with the decimal, while integer division gives you just the whole number part without the remainder.

Why Use Integer Division?

You might be wondering why you would ever want to use integer division. One common reason is when you are interested only in whole number results. For example, if you're writing a program that deals with items that can't be divided, like people or whole apples, you'd use integer division.

Another reason might be performance. Integer division is often faster than floating-point division because it involves simpler arithmetic and doesn't need to handle decimal places.

Working with Remainders

Sometimes, you need to know what the remainder is when you're dividing numbers. You can use the modulo operator % in Python to find out:

# Finding the remainder of 10 divided by 3
remainder = 10 % 3
print(remainder)  # Output: 1

In the pizza example, this would be like saying, "Each person gets 2 slices, and there's 1 slice left over."

Combining Integer Division and Remainders

You can combine integer division and the modulo operator to get both the whole number quotient and the remainder:

# Combining integer division and modulo to get quotient and remainder
slices_of_pizza = 8
friends = 3

slices_per_friend = slices_of_pizza // friends
leftover_slices = slices_of_pizza % friends

print(f"Each friend gets {slices_per_friend} slices")
print(f"There are {leftover_slices} slices left over")

In this code, you'd get an output saying each friend gets 2 slices and there are 2 slices left over.

Common Mistakes and How to Avoid Them

A common mistake beginners make is confusing // with /. Remember, // is for integer division (no decimals), and / is for regular division (with decimals). Another mistake is assuming integer division will round to the nearest whole number. As we have seen, it always rounds down to the lower number.

To avoid these mistakes, always double-check which division operator you're using and remember how Python handles rounding with integer division.


Integer division is like a quirky character in the world of Python—a bit different from what you might expect but incredibly useful in the right situations. It's like sharing pizza slices; you can't deal with fractions, so you stick to whole numbers. This functionality is essential for tasks that require discrete values or when performance matters.

In your programming journey, understanding the nuances of operations like integer division can make your code more efficient and your logic clearer. So next time you're dividing up resources or calculating intervals, remember the // operator and its unique way of slicing through numbers, just like a pizza cutter through a hot, cheesy pie. Happy coding, and may your divisions be as straightforward as integer division in Python!