public static int numFives (double[] a) {
    return numFives (a, 0, 0);
  }
  private static int numFives (double[] a, int i, int result) {
    if (i>=a.length) 
      return result;
    if (a[i] == 5.0) 
      result = result+1;
    result = numFives (a, i+1, result);
    return result;
  }