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Counting Quadruplets (Posted on 2010-08-20) Difficulty: 3 of 5
Each of A, B, C and D is a positive integer with the proviso that A ≤ B ≤ C ≤ D ≤ 20.

Determine the total number of quadruplets (A, B, C, D) such that A*B*C*D is divisible by 50.

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

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re: Solution | Comment 6 of 11 |
(In reply to Solution by Praneeth)

I am not sure where the disagreement lies, but I think it may be in your statement "at least 2 must be from set p" if perhaps that is being interpreted as "two different values from set p".  This would exclude e.g. (6  9  10  10) = 1500, and many more where the same member of p occurs twice (or even three or four times), but the other integers are not in p.  Perhaps we have different readings of the puzzle text.
  Posted by ed bottemiller on 2010-08-20 19:06:32

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