I need a simple javascript that will take a user-inputted number and then divide it by 900 and round up to the next integer.

For example, a customer wants 2000 units and we sell units in packages of 900. So the customer would type in 2000 in a box and press "submit" and a result would be displayed notifying them to purchase 3 boxes. (2000/900 = 2.22 and since we don't break up boxes, they would need to purchase 3 full boxes)

(Exception to rounding up... Obviously if the customer wanted a perfect factor of 900, I wouldn't need to round up an integer... if the customer ordered 1800 they would need 2 boxes)

Help???