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Counting triplets (Posted on 2010-03-31) Difficulty: 3 of 5
For how many ordered triplets (a, b, c) of positive integers, each less than 10 is the product abc divisible by 20?

See The Solution Submitted by Ady TZIDON    
Rating: 4.0000 (1 votes)

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Old dog, new tricks? | Comment 6 of 7 |
My last math class (other than in computing) was almost sixty years ago, and I do not recall the phrase "ordered pairs" or "ordered triplets" etc. so just had to guess what was intended. Looking on google now I did not find anything useful on this, to remove any ambiguity).  If permutations are pemitted/intended, of course that allows more than the 20 sequences  I found.  Is this something from the "new math" ?
  Posted by ed bottemiller on 2010-03-31 15:50:35
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