Carcass wrote:
What is the least positive integer that is not a factor of \(20!\) and is not a prime?
(A) 19
(B) 23
(C) 36
(D) 46
(E) 58
20! = (20)(19)(18).....(3)(2)(1)
We need to find a number which does not divide 20!
Let us check the option choices;
A. 19we can see we have 19 in 20!
B. 23even though we do not have 23 in 20!, but the number we are looking for is not prime
C. 3636 = (2)(18) = (3)(12) = (4)(9) and we have all the numbers in 20!
D. 4646 = (2)(23)
we have 2 in 20! but not 23, also 46 is not a prime
Hence, option D