# Java.math.BigInteger.probablePrime() Method

## Description

The java.math.BigInteger.probablePrime(int bitLength, Random rnd) returns a positive BigInteger that is probably prime, with the specified bitLength. The probability that a BigInteger returned by this method is composite does not exceed 2-100.

## Declaration

Following is the declaration for java.math.BigInteger.probablePrime() method.

```public static BigInteger probablePrime(int bitLength, Random rnd)
```

## Parameters

• bitLength − bitLength of the returned BigInteger.

• rnd − Source of random bits used to select candidates to be tested for primality.

## Return Value

This method returns a BigInteger of bitLength bits that is probably prime.

## Exception

ArithmeticException − If bitLength < 2.

## Example

The following example shows the usage of math.BigInteger.probablePrime() method.

```package com.tutorialspoint;

import java.math.*;
import java.util.*;

public class BigIntegerDemo {

public static void main(String[] args) {

// create a BigInteger object
BigInteger bi;

// create and assign value to bitLength
int bitLength = 3;

// create a random object
Random rnd = new Random();

// assign probablePrime result to bi using bitLength and rnd
// static method is called using class name
bi = BigInteger.probablePrime(bitLength, rnd);

String str = "ProbablePrime of bitlength " + bitLength + " is " +bi;

// print bi value
System.out.println( str );
}
}
```

Let us compile and run the above program, this will produce the following result −

```ProbablePrime of bitlength 3 is 5
```

java_math_biginteger.htm