char input[]="171A9253A3";
char mId[11];

void setup() {
  Serial.begin(9600);
  // put your setup code here, to run once:
  int offset[11] = { 10,9,8,7,6,5,4,3,2,1,0 };
  for(int i=0;i<11; i++){
    mId[i-1]=input[offset[i]];
  }
  unsigned long s=((3 * pow(16,9))+(10 * pow(16,8)) + (3 * pow(16,7))+(15 * pow(16,6)) + (2 * pow(16,5))+(9 * pow(16,4)) + (10 * pow(16,3)) +(1 * pow(16,2)) + (07 * pow(16,1))+ 1);
  Serial.println(s);
  Serial.println(mId);
}

void loop() {
  // put your main code here, to run repeatedly:

}