Plz help Im so confused
Find the number of ways of arranging the numbers 1,2 ,3, 4, 5, 6, 7, 8, 9 in a row so that the product of any two adjacent numbers is even.
There are 1364 possible arrangements.
1, 3, 5, 7, 9 ==5 odd numbers
2, 4, 6, 8 ==4 even numbers.
The 9-number arrangements must begin with an odd number and end with an odd number:
Therefore, there are: 5! * 4! ==120 * 24 ==2,880 such arrangements possible.
