How to call a method when a value reaches multiples of 5

I have Firebase database where a number value is stored for a specific user. I want to show an advert when the value reaches multiples of 5, starting at 0.

I can get it to call the method from for the first multiple of 5 using an if statement like this

  if (ads < 5 && dls > 5) {
        Toast.makeText(c,"Testing it worked here",Toast.LENGTH_LONG).show();

How can I edit this so it calls it at 10, 15, 20, 25 and so on?