code: private static BigInteger bigTenToThe(int n) {
          if (n < 0)
              return BigInteger.ZERO;
  
          if (n < BIG_TEN_POWERS_TABLE_MAX) {
              BigInteger[] pows = BIG_TEN_POWERS_TABLE;
              if (n < pows.length)
                  return pows[n];
              else
                  return expandBigIntegerTenPowers(n);
          }
  
          return BigInteger.TEN.pow(n);
      }
docs: Return 10 to the power n, as a {@code BigInteger}.
  
  @param  n the power of ten to be returned (>=0)
  @return a {@code BigInteger} with the value (10<sup>n</sup>)