Number

The round() function in Python is used to round numbers. It can round both integers and floating-point numbers.

Syntax of the function round()

round(number, ndigits)

number — the number to round up

`ndigits’ (optional) — the number of decimal places. If not specified, the number is rounded to the nearest integer.

Rounding to the nearest integer

result = round(3.14159)
print(result) # Output: 3

Rounding with the number of decimal places

result = round(3.14159, 2)
print(result) # Output: 3.14

Rounding to the nearest larger integer

result = round(3.7)
print(result) # Output: 4

Rounding up negative numbers

result = round(-2.7)
print(result) # Output: -3

Rounding to the nearest even number if the number is exactly in the middle

result = round(2.5)
print(result) # Output: 2

If ndigits' is not specified, round()` rounds to the nearest integer.

If ndigits is specified, rounding occurs to the specified number of decimal places.

If the number is exactly in the middle between two possible variants (for example, 2.5), Python rounds to the nearest even number (this is called “bank rounding”)

ndigits

Examples with ndigits', the second parameter of the round()` function

Rounding to one decimal place

result = round(3.14159, 1)
print(result) # Output: 3.1

Rounding to three decimal places

result = round(3.14159, 3)
print(result) # Output: 3.142

Rounding to zero decimal places is equivalent to rounding to an integer

result = round(3.14159, 0)
print(result) # Output: 3.0

The round() function is often used for:

Simplifying numbers for output.

Limits on the number of decimal places in calculations.

Data preparation for further processing.