R
P
what is the next letter e h l q
X
S
c
Q
The next (and last) letter is C. Just as a countdown counts backwards, this series is "countdown" spelled backwards.
c is next
y
S
T
It's the letter D of course! Haven't you heard of Jason D?!
The question is stated wrong.It should be: "What is the next letter in the series O T T F F ?", and the answer is " S ".These are the initial letters of the words: One Two Three Four Five, followed by Six.