Turn the dial to the right, or clockwise, until it reaches zero.
Turn the dial to the left, or counter-clockwise, a number of times equal to the amount of numbers in the combination. Every time you reach the first number of the combination, it counts as one turn. So if there are four numbers in the combination, and the first number is 33, you would turn the dial left and pass 33 three times before coming to rest on 33 the fourth time around.
Turn the dial to the right a number of times equal to the amount of numbers in the combination, minus one. If there are four numbers in the combination, you would turn the dial to the right and pass the second number twice before coming to rest on it the third time around.
Continue to reverse directions and subtract one from the number of spins per direction. When you reach the last number in the combination, the safe should open.