class validateIBAN{
 
  private static int calcMod97(String D) {
    String N = D.substring(0, 9);
    int remainder;
    int end = D.length() - 1;
    int pos = 9;
    boolean last = false;
    while(true) {
      remainder = Integer.valueOf(N) % 97;
      if(!last) {
        if((pos + 7) < end) {
          N = String.valueOf(remainder).concat(D.substring(pos, pos + 7));
          pos = pos + 7;
        } else {
          N = String.valueOf(remainder).concat(D.substring(pos));
          pos = end;
          last = true;
        }
      } else {
        break;
      }
    }
    return remainder;
  }
  public static void main(String[] args) {
    String IBAN1 = "00120345030000067890142807";
    String IBAN2 = "20389433376000130761142872";
    System.out.println(IBAN1);
    System.out.println(calcMod97(IBAN1));
    System.out.println(IBAN2);
    System.out.println(calcMod97(IBAN2));
  }
}

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