Market Products receives kits of parts from a supplier. Each kit contains all of the small parts required for an assembly. The kits are boxed in quantities of 50, and boxes are delivered directly to point of use racks in the assembly area. Each time a box is opened, a replenishment order is sent to the supplier. The average daily demand is 45. The lead time on replenishment from the supplier (total order and delivery time) is 10 days. The company likes to hold enough stock for 20% safety margin. Assuming one kanban card per box, how many cards should there be?