Question 864873: If each of the 10 digits is chosen at random, how many ways can you choose
the following numbers?
(a) A two-digit code number, repeated digits permitted.
(b) A three-digit identification card number, for which the first digit cannot
be a 0.
(c) A four-digit bicycle lock number, where no digit can be used twice.
(d) A five-digit zip code number, with the first digit not zero
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! If each of the 10 digits is chosen at random, how many ways can you choose
the following numbers?
(a) A two-digit code number, repeated digits permitted.:: 10^2 = 100
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(b) A three-digit identification card number, for which the first digit cannot
be a 0.:: 9*10^2 = 900
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(c) A four-digit bicycle lock number, where no digit can be used twice.
:: 10*9*8*7 = 5040
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(d) A five-digit zip code number, with the first digit not zero
:: 9*10^4 = 90,000
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Cheers,
Stan H.
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