# Java.math.BigInteger.probablePrime() method in Java

Prerequisite : BigInteger Basics The probablePrime() method will return a Biginteger of bitLength bits which is prime. bitLength is provided as parameter to method probablePrime() and method will return a prime BigInteger of bitLength bits. The probability that a BigInteger returned by this method is composite and does not exceed 2^-100. Syntax:
`public static BigInteger probablePrime(int bitLength, Random rnd)`
Parameters: This method accepts two parameters as shown in the above syntax and described below.
• 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.
Below program illustrate the probablePrime() method:
 `import` `java.math.*; ``import` `java.util.Random; ``import` `java.util.Scanner; `` ` `public` `class` `GFG { `` ` `    ``public` `static` `void` `main(String[] args) ``    ``{ `` ` `        ``Scanner sc = ``new` `Scanner(System.in); `` ` `        ``// create a BigInteger object ``        ``BigInteger biginteger; `` ` `        ``// create a integer value for bitLength ``        ``int` `length = ``4``; `` ` `        ``// create a random object ``        ``Random random = ``new` `Random(); `` ` `        ``// call probablePrime method to find next probable prime ``        ``// whose bit length is equal to bitLength provided as parameter. ``        ``biginteger = BigInteger.probablePrime(length, random); `` ` `        ``String result = ``"ProbablePrime whose bit length is "``                        ``+ length + ``" = "` `+ biginteger; `` ` `        ``// print result value ``        ``System.out.println(result); ``    ``} ``}`

Output:
```ProbablePrime whose bit length is 4 = 13
```
Reference:https://docs.oracle.com/javase/7/docs/api/java/math/BigInteger.html#probablePrime(int, %20java.util.Random)

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