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Riddle: What are the next three letters in this combination? OTTFFSS

Answer: E N T (Each letter represents the first letter in the written numbers: One, Two, Three, Four, Five, etc.).

Source: https://www.riddles.com/index.php/10499

What are the next three letters in this combination? OTTFFSS — Line up by Jayanth v1.

Riddle: What are the next three letters in this combination? OTTFFSS Answer: E N T (Each letter represents the first letter in the written numbers: One, Two, Three, Four, Five, etc.). — by Jayanth v2.