since there are 3 slots and each slot has 30 positions:
dial 1 can have a max of 30 possible outcomes, and so can dial 2 and 3
hence all the dial have 30 possible outcomes
total combinations = total outcomes of slot 1 X total outcomes of slot 2 X total outcomes of slot 3/ 3!
total combinations = 30 * 30 * 30 / 3 X 2 X 1
total combinations = 9000/3 X 2
total combinations = 1500
hence, there is a total of 1500 different combinations of the 3 slots
the combination required is 1 from the 1500
hence the odds are 1/1500