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Help plz with counting

 

Find the number of ways of arranging the numbers 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 in a row so that the product of any two adjacent numbers is even or a mutliple of 3

 Mar 30, 2023
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(1,5), (5,1), (1,7), (7,1), (5,7), (7,5) ==6 - any of these 6 pairs included in 10! permutations must be removed.

 

10!  -  [9! * 6]  +  [8! * 6] ==1,693,440 - total number of ways or permutations.

 Mar 31, 2023

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