title: Javascript one discounted order out of 11
body: <p>Good morning. I am a junior dev and I really cannot figure out how to implement this functionality: imagine a Pizza Restaurant, the owner wants to provide a discount of let's say 7% every 11 orders (or another number he wants) for every user. So the discount would be applied at the 11th, 22th,..., 2750th order. Plus perhaps he would like to change at a certain point and decids to apply the discount every 8 orders instead of 10. I don't really know how to solve it. Any suggestion?</p>