## Introduction

We, humans, like things that are simple, easy to make sense of, that are easy to understand. And for us, it's harder to use just any decimal number in calculations, even while calculating length or while calculating our weight on the weighing machine. Hence we generally prefer to use round numbers.

In this blog, we will study the round() function in Python. It is a function that helps to round off a number and eliminates the least significant digits. This simplifies the notation while keeping very close to the original value.

Must read, __Divmod in Python__, and __Convert String to List Python__

## What is Round Function in Python?

The round() function in __Python__ is a built-in function that allows you to round a number to a specified number of decimal places or to the nearest integer. It takes two arguments: the number you want to round, and the number of decimal places you want to round to. If you omit the second argument, it defaults to zero, and the number is rounded to the nearest integer. The round() function uses the rounding half to even method by default, which means that if the number you're rounding is exactly halfway between two possible rounding values, the result is rounded to the nearest even number. This behaviour can be changed by specifying a different rounding method using the decimal module. The round() function is useful when you need to perform calculations that require precision and rounding of decimal values.

## Python round() Syntax:

```
round(number, ndigits)
>>> round(3.14159) # round to the nearest integer as ndigits is not provided
3
```

## Python round() Function Parameters:

As we can see in the syntax that there are two parameters i.e., **number and ndigits**. The **number **parameter is the value that you want to round. It can be an integer or a floating-point number. The **ndigits** parameter is optional. It specifies the number of decimal places to which you want to round the number. If **ndigits** is not provided, the round() function will round the number to the nearest whole number. Let us take an example to understand round() with a single parameter and two parameters:

This will produce the following output:

```
4
4.208
4.2078
```

## Python round() Function Return Value

The round() function returns the-

- If the value of digits is not provided, the round function will return the nearest integer to the given number.
- The number is rounded off to the given digits if the digits parameter is provided.

**Example**

The number 3.5, when rounded to the nearest whole number digit, is 4. Similarly, for 1.6, it will be 2.

```
Input
3.5
1.6
Output
4
2
```

Now let's practice some examples of the round() function when the second parameter is not defined.

**Implementation in Python**

**Output**

Now it's time to practice some examples of the round() function when the second parameter is given. You can compile it with online python compiler.

**Implementation in Python**

**Output**

**Round() Function Example with Float Numbers**

**Round() Function Example with Integer Values**

**Round() Function Example with Negative Numbers**

**Round() Function Example with Numpy Arrays**

Apart from this, there are more unique ways to round a number. This python decimal module helps in handling decimal numbers more accurately. Let's discuss a few of them.

ROUND_CEILING | It will round towards infinity or round up. |

ROUND_DOWN: | It will round the value towards zero or truncate. |

ROUND_FLOOR: | It will round towards -infinity or round down. |

ROUND_HALF_DOWN | It will round to the nearest with ties going toward zero. |

ROUND_HALF_EVEN | It will round to the nearest value heading to the nearest even integer. |

ROUND_HALF_UP | It will round to the nearest value, with the value going away from 0(zero). |

ROUND_UP | It will round up to where the value of the floating point will go away from zero. |

ROUND_05UP | It will round up whether the last digit is 0 or 5. Otherwise, it will round down. |

**Round() Function Example with Decimal Module**

The Decimal module is employed for performing tasks related to decimal floating-point operations, ensuring precise rounding. To utilize it, we must begin by importing it from the standard library module Decimal. Here's an example of using the round() function with the decimal module in Python.

**Output:**

### Error and Exceptions

How the errors and exceptions can occur when using the **round()** function in Python:

**TypeError**example:

```
>>> round('3.14')
TypeError: type str doesn't define __round__ method
```

Here, we are trying to round a string value, which is not possible. This results in a **TypeError** exception.

**2. ValueError** example:

```
>>> round(3.14159, '2')
ValueError: ndigits must be an integer
```

In this case, we passed a non-integer value as the second argument to the **round()** function. This causes a **ValueError** exception to be raised.

**3. OverflowError** example:

```
>>> round(10**1000)
OverflowError: int too large to convert to float
```

In this case, we passed a very large integer value to the **round()** function, which cannot be represented as a floating-point number. This causes an **OverflowError** exception to be raised.

**4. NameError** example:

```
>>> round(3.14159)
NameError: name 'round' is not defined
```

Here, we are trying to use the **round()** function without importing it first. This results in a **NameError** exception.

## Practical Applications:** **

The **round()** function in Python is a useful tool for handling numerical data and performing mathematical calculations. Here are some practical applications of the **round()** function in Python:

**Financial calculations:**In financial applications, it is often necessary to round numbers to a certain number of decimal places. For example, when calculating interest rates or currency conversions, you may need to round values to two decimal places. The**round()**function is ideal for this purpose.**Data analysis:**When working with large data sets, it is often necessary to round data to a certain number of decimal places. This can help to reduce noise in the data and make it easier to work with. The**round()**function is commonly used in data analysis for this purpose.**Scientific calculations:**In scientific applications, it is important to perform calculations with a high degree of precision. The**round()**function can be used to round values to a certain number of decimal places to achieve this level of precision.**User interfaces:**In user interfaces, it is often necessary to display numerical data to the user in a user-friendly format. The**round()**function can be used to format numerical values in a way that is easy for the user to read and understand.

Overall, the **round()** function is a versatile tool that can be used in a wide range of applications where numerical data is involved.

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Now itâ€™s time for some frequently asked questions.

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## Frequently Asked Questions

### Why is round 2.5 is 2 in Python?

In Python, round(2.5) results in 2 because it uses the "round half to even" or "banker's rounding" method, which rounds to the nearest even number in case of a tie.

### How do you round up to 0.5 in Python?

We can round up to the nearest 0.5 in Python using the round() function with some simple arithmetic. For example, we can round up number 2.3, by doing round(2.3 * 2) / 2 this will produce a result of 2.5.

### What does the round () function return?

The round() function in Python returns a rounded version of a number. The exact return value depends on the arguments provided to the function.

## Conclusion

This article taught us to calculate the Round() function in Python. We have discussed the approach using some examples in python languages. To enhance your knowledge of python programming, check out these articles-

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