sat math permutations

[Jack]

How many different 4-digit numbers can be formed using all of the following numbers?
0,1,1,9
(A) 4
(B) 12
(C) 16
(D) 24

thanks

[miranda]

In this case we have permutations since the order matters. Additionally we must divide the number of permutations by 2! Since the digit “1” appears twice.
Therefore the answer is (B).

[Jack]

thank you!!