How to Round to n Decimal Places in Python Easily

In Python, you can round a number to n decimal places using the built-in round() function by passing the number and n as arguments, like round(number, n). This returns the number rounded to the specified decimal places as a float.

Syntax

The round() function takes two arguments:

• number: The float or integer you want to round.
• ndigits: The number of decimal places to round to (an integer or None).

It returns the rounded number as a float if ndigits is specified, or an integer if ndigits is None.

python

rounded_value = round(number, ndigits)

Example

This example shows how to round a float to 2 decimal places using round(). It prints the original and rounded values.

python

number = 3.14159
rounded_number = round(number, 2)
print("Original number:", number)
print("Rounded to 2 decimal places:", rounded_number)

Output

Original number: 3.14159
Rounded to 2 decimal places: 3.14

Common Pitfalls

One common mistake is expecting round() to always return a string or to format the number visually. It returns a float, which may still display more decimals depending on printing.

Also, due to how floating-point numbers work, some results may look unexpected (like rounding 2.675 to 2 decimals gives 2.67).

python

print(round(2.675, 2))  # Outputs 2.67, not 2.68

# To format as string with fixed decimals use format or f-string:
print(f"{2.675:.2f}")  # Outputs '2.68'

Output

2.67
2.68

Quick Reference

Summary tips for rounding in Python:

• Use round(number, n) to round to n decimals.
• Result is a float, not a formatted string.
• For display, use format() or f-strings like f"{number:.2f}".
• Floating-point rounding can have small precision quirks.

Key Takeaways

Use round(number, n) to round to n decimal places in Python.

round() returns a float, not a formatted string.

For consistent display, format numbers with f-strings or format().

Floating-point arithmetic can cause small rounding surprises.

Always test rounding results when precision matters.