This word riddle asks for a six-letter word that turns into something meaning 12 when one letter is removed.
The answer is DOZENS.
“Dozens” has six letters. Remove the final letter S and you are left with DOZEN, which means 12.
Answer: DOZENS.
The trick is that “becomes 12” does not mean the word itself turns into the number 12. It turns into a word that represents the number 12.


