Divide 15 by 4.
Since the quotient is 3 remainder 3, put 0 to the remainder and then divide it again by 4.
Since 30 divided by 4 is 7 remainder 2, put 0 to the remainder and then divide it again by 4.
The quotient of 20 and 4 is 5.
Thus, combining all the obtained quotients, we have the following: