SOLUTION: Hey guys would be great if you could help me out with the following problem:
4-digit code with 0-9 as possible digits. How many codes are there that
contain the digit "0" exactly
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-> SOLUTION: Hey guys would be great if you could help me out with the following problem:
4-digit code with 0-9 as possible digits. How many codes are there that
contain the digit "0" exactly
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Question 644763: Hey guys would be great if you could help me out with the following problem:
4-digit code with 0-9 as possible digits. How many codes are there that
contain the digit "0" exactly twice?
I found that (10^4) - (9^4) = 3439 which is the number of codes with "0" at least once. Any help on how I would go about solving two instances of "0" would be awesome.
Thanks,
Rob Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! the codes will look like one of these:
00xx
xx00
0x0x
x0x0
x00x
0xx0
where the x's can't be 0, but
they can be 1-9
-------------
So there are possible
codes for each of these 6 choices
there are 6*81 = 486 possible
codes altogether
