Next letter

A nice short puzzle, perfect for posing at the start of class.

Puzzle

What are the next letters in the sequence: O T T F F S S E?

Hint

The next letter is N

Answer

N T E T T ...

Solution

The letters in the sequence are the initials of the natural numbers: One, Two, Three, etc. So the sequence continues: N T E T T F F S S E N T.