Question 321191: stan..if you can help me out once more i would appreciate so much :)
a combination lock has digits from 0 to 39. three numbers are required to open.
how many combinations are possible if you cannot repeat any digits?
how many combination are possible if you cannot have the same digit twice in a row?
this is what i came up with..59,280 for first one and can't figure out second one:(
Answer by Alan3354(69443)   (Show Source):
You can put this solution on YOUR website! a combination lock has digits from 0 to 39. three numbers are required to open.
how many combinations are possible if you cannot repeat any digits?
40*39*38 = 59280
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how many combination are possible if you cannot have the same digit twice in a row?
Call the number F, S and T for 1st, 2nd and 3rd
F is 1/40
S is any but F, = 1/39
T is any but S, = 1/39
40*39*39 = 60840
this is what i came up with..59,280 for first one and can't figure out second one:(
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