A Permutations and combinations question

dknight

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Sep 13, 2013
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Find the number of 6 digit numbers that end in 21(eg-573621) , without repetition of digits
 
Find the number of 6 digit numbers that end in 21(eg-573621) , without repetition of digits

Since last two digits take up 2 & 1 and there is no repetition - we need to make four digit numbers from remaining 8 numbers.

We can fill the left most digit 7 numbers (cannot have zero in the left most digit)

We can fill the next position with 7 numbers (one number used at front but 0 is back in play)

We can fill the next position with 6 numbers....

We can fill the next position with 5 numbers....

Now what.....

Please share your work with us .

If you are stuck at the beginning tell us and we'll start with the definitions e.g. define retained earnings.

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