Multiples of counter

hello. i am trying to learn flash for my lectures, but i got stuck somewhere and was hoping that someone could help; how can make a counter that increments only for multiples of say, only 500 [ i.e 500, 1000, 1500, 2000, 2500… ]. that’s the cod ei use, but it’s no good;

 
 if (score == 500 || score == 1000 || score == 1500 || score == 2000 || score == 2500 || score == 3000 || score == 3500 || score == 4000) {
  shield++;
  maxAst++;
 }

any help, please?