GAMT Prep pp 01-41 (PS)

[GC06]

All of the stocks on the over-the-counter market are designated by either a 4-letter or a 5-letter code that is created by using the 26 letters of the alphabet. Which of the following gives the maximum number of different stocks that can be designated with these codes?

(A) 2(26^5)
(B) 26(26^4)
(C) 27(26^4)
(D) 26(26^5)
(E) 27(26^5)

答案是C
我選B 請問不是26^4 +26^5 嗎?

[hey]

答案是26^4+26^5沒錯, 但其可再進一步合併
26^4+26^5=26^4+26*26^4=(1+26)*26^4=27(26^4)
所以答案是(C)