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That's a lotta numbers! (Posted on 2006-04-14) Difficulty: 2 of 5
Consider all nine-digit numbers consisting of one each of the digits 1 through 9.

What is the sum of these numbers?

See The Solution Submitted by Jer    
Rating: 3.2500 (4 votes)

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Hints/Tips Is this it? | Comment 2 of 10 |
(In reply to Some Hints For Solving The Problem by K Sengupta)

OK, so there are 9! permutations of digits.  In each place, 1/9 (40320) of them will be a 9, 1/9 will be an 8...etc.

The sum of the digits 1-9 is 45, so I'm guessing the sum we're looking for is:

     4500000000
      450000000
       45000000
        4500000
         450000
          45000
           4500
            450
     +       45
     ----------
     4999999995
     x    40320
     ----------
201599999798400
Did I screw that up?
 

  Posted by tomarken on 2006-04-14 11:49:48
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