To state how many times per unit of time something happens, use the #-declension noun рђз and the preposition в with the Accusative form of the word for the time unit. Note that рђз has an irregular Gen. Plur. form, рђз (like the Gen. Plur. солдђт, сапћг, волћс, etc.)
двђ рђза в дљнь twice a day
четІре рђза в недљлю four times a week
пїть рђз в мљсяц five times a month