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#Large Factorials

In mathematics, the factorial of integer n is written as n!. It is equal to the product of n and every integer preceding it. For example: 5! = 1 x 2 x 3 x 4 x 5 = 120

Your mission is simple: write a function that takes an integer n and returns the value of n!.

You are guaranteed an integer argument. For any values outside the non-negative range, return null, nil or None (return an empty string "" in C and C++). For non-negative numbers a full length number is expected for example, return 25! = "15511210043330985984000000" as a string.

For more on factorials, see http://en.wikipedia.org/wiki/Factorial

import java.math.BigInteger;

public class Kata
{

  public static String Factorial(int n) {
      BigInteger result = BigInteger.valueOf(1);
      for (int i = 1; i <= n; i++)
          result = result.multiply(BigInteger.valueOf(i));
      return result.toString();
  }

}