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How many different ways can a nine digit number be written?

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For example : 121212121, order doesnt matter how many different ways can you arrange the digets?
Too many to count would be my best guess.
9 times 9 times 9 times 9 times 9 times 9 times 9 times 9 times 9 = 387 420 489

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Other answers:

Order doesn't matter and there's repetition
There are 1,000,000,000 different 9-digit numbers, ranging from 000,000,000 to 999,999,999.
That doesn't really help
9! so it would be 9x8x7x6x5x4x3x2x1=362880
since there is 4 2's and 5 1's wouldnt some overlap though?
no it shouldnt
Zarkon...any input at all??
are you looking to find the number of arrangement of 121212121 or any 9 digit number. The first is trivial...the second is a much longer computation
number of arrangement of 121212121. I don't remember how to do it.
uh oh I did \[\frac{9!}{4!} + \frac{9!}{5!}\]
if you wanted to arrange 112223333 \[\frac{9!}{2!3!4!}\]
multinomial coefficients
what is exactly meant by order doesn't matter?
is 12 = 21 if order doesn't matter?
how would you do it for 121212121 if order matters
so if you didn't care about the order of 12121212 you would treat all the \(\frac{9!}{5!4!}\) ways to arrange it as being the same.
doesn't involve nPr or nCr?
hmm 5 1s and 4 2s total 9 position is it \[\frac{9!}{4!} + \frac{9!}{5!}\]? (order matters)
I am bad at combinatorics :-/

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