Table of Contents
In this tutorial, we will learn about the Python round() function with the help of examples.
The round() function returns a floating-point number rounded to the specified number of decimals.
Example
1 2 3 4 5 6 7 | number = 13.46# round the numberrounded_number = round(number)print(rounded_number)# Output: 13 |
1. round() Syntax
The syntax of the round() function is:
1 | round(number, ndigits) |
2. round() Parameters
The round() function takes two parameters:
- number – the number to be rounded
- ndigits (optional) – number up to which the given number is rounded; defaults to 0
3. round() Return Value
The round() function returns the
- nearest integer to the given number if
ndigitsis not provided - number rounded off to the
ndigitsdigits ifndigitsis provided
4. Example 1: How round() works in Python?
1 2 3 4 5 6 7 8 | # for integersprint(round(10))# for floating pointprint(round(10.7))# even choiceprint(round(5.5)) |
Output
1 2 3 | 10116 |
5. Example 2: Round a number to the given number of decimal places
1 2 | print(round(2.665, 2))print(round(2.675, 2)) |
Output
1 2 | 2.672.67 |
Note: The behavior of round() for floats can be surprising. Notice round(2.675, 2) gives 2.67 instead of the expected 2.68. This is not a bug: it’s a result of the fact that most decimal fractions can’t be represented exactly as a float.
When the decimal 2.675 is converted to a binary floating-point number, it’s again replaced with a binary approximation, whose exact value is:
1 | 2.67499999999999982236431605997495353221893310546875 |
Due to this, it is rounded down to 2.67.
If you’re in a situation where this precision is needed, consider using the decimal module, which is designed for floating-point arithmetic:
1 2 3 4 5 6 7 8 9 | from decimal import Decimal# normal floatnum = 2.675print(round(num, 2))# using decimal.Decimal (passed float as string for precision)num = Decimal('2.675')print(round(num, 2)) |
Output
1 2 | 2.672.68 |
