All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars
 perplexus dot info

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.

 No Solution Yet Submitted by K Sengupta Rating: 4.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
 re: wrong Solution | Comment 9 of 11 |
(In reply to Solution by hoodat)

You say:
""In order to be divisible by 50, two of the integers must be some combination of 5,10,15, & 20.  There are 6 combinations of this [4!/(2!2!)].  Once one of these pairs is picked, there are 153 combinations of the remaining integers [18!/(2!16!)].  This yields 918 total"

WRONG !!
Where are (20,20,20,20)  or  (5,5,5,10) and hundreds of others you have missed???

P.S. Charlie's result is transparent and 100% correct.

Analytical verification is not so easy.

 Posted by Ady TZIDON on 2010-08-20 20:21:16

 Search: Search body:
Forums (0)