The round() function is used for rounding off numbers up to a specified number of digits after the decimal point.

Syntax:

round(number, digits)

number - the number to be rounded. It is a required parameter.

digits - the number of decimals to use when rounding the number. This is an optional parameter. The default is 0.

Return value:

The round() function's return value depends upon the value of digits. It always returns a number that is either a float or an integer.

x = 3.14159

rounded_1 = round(x)  # Rounds to the nearest whole number
print(rounded_1)     # returns 3

rounded_2 = round(x, 2)  # Rounds to 2 decimal places
print(rounded_2)        # returns 3.14

rounded_3 = round(x, 4)  # Rounds to 4 decimal places
print(rounded_3)        # returns 3.1416

• If the input is an integer, the return value is also an integer.

• If the input is float, the output depends on digits.

• If digits is not specified, an integer is returned, else a floating-point number is returned.

Note:

If there are two equally close values to round to, python will round to the nearest even value.

y = 2.5

rounded_4 = round(y)  # Rounding 2.5 to the nearest whole number
print(rounded_4)     # returns 2

Here, round() rounds 2.5 to the nearest whole number, which is 2. Since 2 and 3 are equally close, it rounds down to the nearest even number. This behaviour is known as "round half to even" or "ties to even."