A certain stock exchange designates each stock with one-, two-, or three-letter code, where each letter is selected from the 26 alphabet. If the letters may be repeated and if the same letters used in a different order constitute a different code, how many different stocks is it possible to uniquely designate with these codes?
stock with one-- 26
two-, 26*25= 650
or three-letter code, 26*25*24= 15,600
the total is 16,276 ... your option (d) is 16,302 thats intriguingly 26 more than my answer ... now i am probably doing something wrong but i can't figure it out and if you do, do post here b/c i am sort of curious now.