We received some fun entries for possible future puzzles for the Brain Game, but we could use more. If you have one, please send it to me at trivia@mentalfloss.com. If your submission makes the cut, I'll give you full credit and will also send you the T-shirt of your choice from the mental_floss store upon publication. Thanks!

On to today's Brain Game. It's fairly straightforward: Provide the sixth (and last) letter of the English alphabet in the following sequence:

F, L, M, N, S, ?.

Here is the ANSWER.

THE ANSWER: X.

These are the six letters of the English alphabet which, when pronounced out loud, begin with a short "e" sound: EF, EL, EM, EN, ES, and EKS.