multiplicativePersistenceOf.dart

void main() {
  int resultPersistance;

  resultPersistance = multiplicativePersistenceOf(489);
  print("multiplicativePersistenceOf(489) =$resultPersistance");
  resultPersistance = multiplicativePersistenceOf(912);
  print("multiplicativePersistenceOf(912) =$resultPersistance");
  
}


int multiplicativePersistenceOf(int value) {
  assert(value > 0);

  int temp = value;
  int result = 0;
  while (getLength(temp) > 1) {
    temp = multiply(temp);
    result++;
  }
  return result;
}

getLength(number) {
  return "$number".length;
}



multiply(int number) {
  int product = 1;
  String num = number.toString();
  List<int> numberArray = [];
  for (int i = 0; i < num.length; i++) {
    numberArray.add(int.parse(num[i]));
  }

  numberArray.map((e) => product = product * e).toList();
  return product;
}