math question about combination safes really confusing need help
You are tasked with opening a safe without knowing the combination. Beginning with the dial at zero, the dial must be turned counterclockwise to the first combination number, then clockwise back to zero), and clockwise to the second combination number, (then counterclockwise back to zero), and counterclockwise again to the third and final combination number, whereupon the door will open immediately. There are 40 numbers of the dial, including the zero.
Without knowing the combination numbers, what is the maximum number of trials required to open the safe? (One trial means one attempt to dial a full three-number combination).