discourse/app/assets/javascripts/locales/ru.js.erb

//= depend_on 'client.ru.yml'
//= require locales/i18n
<%= JsLocaleHelper.output_locale(:ru) %>

I18n.pluralizationRules['ru'] = function (n) {
  if (n == 0) return ["zero", "none", "other"];
  if (n % 10 == 1 && n % 100 != 11) return "one";
  if (n % 10 >= 2 && n % 10 <= 4 && (n % 100 < 10 || n % 100 >= 20)) return "few";
  return "many";
};