We have two slots A and B Slot A has 4 choices (2,4,5,8) Once we make a choice, we can't reuse it. So we have 3 choices left for slot B
Multiply out the values mentioned above to get: 4*3 = 12
Alternatively you can use the nPr formula to get n P r = (n!)/(n-r)! 4 P 2 = (4!)/(4-2)! 4 P 2 = (4!)/(2!) 4 P 2 = (4*3*2*1)/(2*1) 4 P 2 = 24/2 4 P 2 = 12 yielding the same answer
So no matter which method you use, the final answer is 12
