A certain stock exchange designates each stock with a 1, 2 or 3 letter code, where each letter is selected from the 26 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order, constitute a different code, how many diff stocks is it possible to designate with these codes?	Choose the correct choice:
A) 2,951
B) 8,125
C) 15,600
D) 16,302
E) 18,278
1 letter code - 26 (or you can write 26C1)   2 letter code - 26*26=26^2 (or you can write 26C1*26C1=26^2)   3 letter code - 26*26*26=26^3 (or you can write 26C1*26C1*26C1=26^3)   (For 2 letter, for example, you have 26 choices per each letter, it's 26^2 and not 26C2 or 26P2.)   Total =26+26^2+26^3 =18,278   So the answer is 18,278.
<result>E</result>
A certain stock exchange designates each stock with a 1, 2 or 3 letter code, where each letter is selected from the 26 letters of the alphabet. If the letters may be repeated and if the same letters used in a different order, constitute a different code, how many diff stocks is it possible to designate with these codes?