> ## Documentation Index
> Fetch the complete documentation index at: https://hedera-0c6e0218-mintlify-bc559771.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Pseudorandom Number Generator

> Generate verifiable on-chain randomness on Hedera with PrngTransaction, returning 384 random bits or a 32-bit integer within an optional range in the record.

A transaction that generates a pseudorandom number. When the pseudorandom number generate transaction executes, its transaction record will contain the 384-bit array of pseudorandom bytes. The transaction has an optional `range` parameter. If the parameter is given and is positive, then the record will contain a 32-bit pseudorandom integer `r`, where `0 <= r < range` instead of containing the 384 pseudorandom bits.

When the `n`th transaction needs a pseudorandom number, it is given the running hash of all records up to and including the record for transaction `n-3`. If it needs 384 bits, then it uses the entire hash. If it needs 256 bits, it uses the first 256 bits of the hash. If it needs a random number `r` that is in the range `0 <= r < range`, then it lets `x` be the first 32 bits of the hash (interpreted as a signed integer).

The choice of using the hash up to transaction `n-3` rather than `n-1` is to ensure the transactions can be processed quickly. Because the thread calculating the hash will have more time to complete it before it is needed. The use of `n-3` rather than `n-1000000` is to make it hard to predict the pseudorandom number in advance.\\

Reference: [HIP-351](https://hips.hedera.com/hip/hip-351)

| Field     | Description                                                 |
| --------- | ----------------------------------------------------------- |
| **Range** | The specified range to return the pseudorandom number from. |

#### Methods

| Method              | Type    | Requirement |
| ------------------- | ------- | ----------- |
| `setRange(<range>)` | integer | Optional    |
| `getRange(<range>)` | integer | Optional    |

<CodeGroup>
  ```java Java theme={null}
  //Create the transaction with range set
  TransactionResponse transaction = new PrngTransaction()
          //Set the range
          .setRange(250)                
          .execute(client);

  //Get the record
  TransactionRecord transactionRecord = transaction.getRecord(client);

  //Get the number
  int prngNumber = transactionRecord.prngNumber;

  System.out.println(prngNumber);

  //SDK version 2.17.0
  ```

  ```javascript JavaScript theme={null}
  //Create the transaction with range set
  const transaction = await new PrngTransaction()
          //Set the range
          .setRange(250)                
          .execute(client);

  //Get the record
  const transactionRecord = await transaction.getRecord(client);

  //Get the number
  const prngNumber = transactionRecord.prngNumber;

  console.log(prngNumber);

  //SDK version 2.17.0
  ```

  ```go Go theme={null}
  transaction, err := hedera.NewPrngTransaction().
  	// Set the range
  	SetRange(250).
  	Execute(client)
  if err != nil {
  	println(err.Error(), ": error executing rng transaction")
  	return
  }

  transactionRecord, err := createResponse.GetRecord(client)
  if err != nil {
  	println(err.Error(), ": error getting receipt")
  	return
  }

  if transactionRecord.PrngNumber != nil {
  	println(err.Error(), ": error, pseudo-random number is nil")
  	return
  }

  println("The pseudorandom number is:", *transactionRecord.PrngNumber)

  //Version 2.17.0
  ```

  ```rust Rust theme={null}
  // Create the transaction with range set
  let transaction = PrngTransaction::new()
      .range(250)
      .execute(&client)
      .await?;

  // Get the record
  let record = transaction.get_record(&client)?;

  // Get the number
  if let Some(prng_number) = record.prng_number {
      println!("The pseudorandom number is: {:?}", prng_number);
  } else {
      println!("No pseudorandom number returned in the record.");
  }

  // v2.17.0+
  ```
</CodeGroup>