# How to Round a Number in Python

Python doesn’t have a built-in function to round numbers, but you can create one yourself using the int() and math.floor() functions. Here’s how to do it.

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## What is rounding?

Rounding a number simply means finding which number is closest to the number you are rounding, and then replacing your number with that other number. There are many different ways to round numbers, which we will cover in this article. The most common way to round a number is to round it to the nearest whole number.

## Why would you want to round a number in Python?

There are many reasons why you might want to round a number in Python. For example, you might want to calculate an average from a list of numbers and only want to keep the closest whole number. Or you might be working with data that contains rounding errors and want to correct them.

Whatever your reason, Python makes it easy to round numbers. In this article, we’ll show you how to round a number in Python using the built-in round() function.

## How to round a number in Python using the built-in round() function

Rounding numbers is a common task that you’ll likely encounter when working with data. For example, you may want to round a number to the nearest whole number, or to the nearest tenth or hundredth.

Fortunately, Python has a built-in round() function that makes it easy to round a number to the precision you need. In this article, we’ll show you how to use the round() function and give you some examples of how it can be used.

The round() function takes two arguments: The first is the number you want to round, and the second is the precision. The precision is the number of decimal places you want to keep. For example, if you want to round a number to the nearest whole number, you would use a precision of 0.

Here’s an example of how to use the round() function:

“`
>>> x = 3.1415926
>>> print(round(x, 0))
3.0
“`

## How to round a number in Python to a specific decimal place

Python has a built-in round() function that takes two arguments: the number to be rounded and the number of decimal places to round to. If you only specify one argument, Python will round the number to the nearest whole number.

For example, if you want to round the number 3.14159 to two decimal places, you would use the following code:

round(3.14159, 2)

This would return the value 3.14, which is rounded up from 3.13 (because 14 is closer to 15 than it is to 10).

You can also use negative values for the second argument, which will cause Python to round the number to a certain number of digits before the decimal point. For example, if you wanted to round the number 3.14159 to the nearest ten-thousandth, you would use this code:

round(3.14159, -5)

This would return the value 0.00003, which is rounded up from 0.00002 (because 5 is closer to 0 than it is to 10).

## How to round a number in Python to the nearest integer

If you want to round a number in Python to the nearest integer, you can use the built-in round() function. The round() function takes two arguments: the number to be rounded and the number of decimal places to retain. By default, Python rounds to the nearest integer. So, if we want to round 4.5 to the nearest integer, we would use this code:

“`
round(4.5)
“`

This would output 5.0, because 5 is the nearest integer to 4.5.

If we want to keep one decimal place, we would use this code:

“`

## How to round a number in Python up or down

Python provides two built-in functions to help you with rounding numbers: round() and math.floor().

The round() function rounds a number to the nearest whole number. For example, if you want to round 3.14 up to the nearest whole number, you would use the following code:

round(3.14)

This would return the value 4.

If you want to round 3.14 down to the nearest whole number, you would use the following code:

math.floor(3.14)

This would return the value 3.

## How to use the Decimal module to round a number in Python

The Decimal module in Python implements fixed and floating point arithmetic using the model familiar to most programmers where a number is a (possibly very large) integer, exponentiated by a (small) fractional power of ten. The exponent shows how many powers of ten the integer part needs to be multiplied by in order to recover the original number. The reverse operation can be performed by dividing instead of multiplying. So, we can represent 0.01 as follows:

>>> from decimal import Decimal
>>> Decimal(‘0.01’)
Decimal(‘0.01′)
We can also use other notations for numbers:

>>> Decimal(10) # an integer
Decimal(’10’)
>>> Decimal(‘3.14’) # a float literal represented as a string
Decimal(‘3.14’)

## How to use the math.ceil() and math.floor() functions to round a number in Python

If you want to round a number up or down in Python, you can use the math.ceil() and math.floor() functions. The math.ceil() function rounds a number up to the nearest integer, while the math.floor() function rounds a number down to the nearest integer.

To use either of these functions, you need to import the math module first:

import math

Then, you can use either the math.ceil() or math.floor() function by passing in the number you want to round as an argument:

rounded_number = math.ceil(4.2) # Will round up to 5
rounded_number = math.floor(4.2) # Will round down to 4

## What are some other ways to round a number in Python?

There are a few different ways to round a number in Python. The built-in function round() will round a number to the nearest whole number. You can also use the floor() and ceil() functions from the math module to round a number down or up to the nearest whole number, respectively.

If you want more control over how a number is rounded, you can use the decimal module. This module provides the Decimal class, which allows you to specify the precision of a decimal number (i.e., the number of digits after the decimal point). You can then use thequantize() method to round a Decimal instance to a given precision.

Here are a few examples of how to round numbers in Python:

## Summary

This article covers how to round a number in Python. The round() function is the primary method for rounding numbers in Python. It takes twoarguments: the number to be rounded and the number of decimal places to round to. The default behavior is to round to the nearest integer.

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