# 1. Introduction

In this tutorial, we will create a Java program to round a number to *n* decimal places. Rounding is a fundamental operation when we wish to limit the number of decimal places, especially when dealing with monetary values or specific scientific calculations.

# 2. Program Steps

1. Define a class named *RoundNumber*.

2. Inside the class, define the *main* method.

3. Inside the *main* method, declare a *double* variable representing the number to be rounded.

4. Declare an *int* variable *n* representing the number of decimal places to which the number should be rounded.

5. Utilize *Math.round()* method along with *Math.pow()* to round the number to *n* decimal places.

6. Print the original number and the rounded number.

# 3. Code Program

```
public class RoundNumber { // Step 1: Define a class named RoundNumber
public static void main(String[] args) { // Step 2: Define the main method
// Step 3: Declare a double variable representing the number to be rounded
double number = 123.456789;
// Step 4: Declare an int variable n representing the number of decimal places
int n = 3;
// Step 5: Utilize Math.round() and Math.pow() to round the number to n decimal places
double roundedNumber = Math.round(number * Math.pow(10, n)) / Math.pow(10, n);
// Step 6: Print the original and rounded number
System.out.println("Original Number: " + number);
System.out.println("Rounded to " + n + " decimal places: " + roundedNumber);
}
}
```

### Output:

Original Number: 123.456789 Rounded to 3 decimal places: 123.457

# 4. Step By Step Explanation

– *Step 1:* A class named *RoundNumber* is defined.

– *Step 2:* The *main* method is defined within the *RoundNumber* class.

– *Step 3:* A *double* variable *number* is declared, representing the number to be rounded.

– *Step 4:* An *int* variable *n* is declared, representing the number of decimal places to which the number should be rounded.

– *Step 5:* The *Math.round()* method is used in combination with *Math.pow()* to achieve the rounding to *n* decimal places.

– *Step 6:* The original *number* and the *roundedNumber* are printed to the console.