Case 39 · letter riddle · Easy · About 4–7 minutes
A lantern keeper has lost a single brass letter from a sign. Instead of naming it, she leaves three statements about other words. The statements concern written characters, so a silent reading is just as useful as saying the words aloud.
Your answer must be one uppercase letter, not a whole word, a sound, or an object from the illustration.
The keeper’s complete riddle is:
I appear exactly once in LANTERN.
I appear exactly twice in CRESCENT.
I do not appear in LIGHT.
Which letter is missing from the sign?
Use the printed spellings exactly. Count occurrences of the same letter, wherever they fall in a word. There are no hidden spaces, silent-letter rules, different fonts, or alternate spellings. All three statements are true of the intended answer.
The possible letters are the ordinary uppercase alphabet, ABCDEFGHIJKLMNOPQRSTUVWXYZ. You may cross out candidates as soon as one statement rules them out.
The riddle does not require every statement to eliminate a new candidate. A final statement can also confirm a result established by earlier ones. Your task is to find the letter satisfying the complete set and show why no second letter does.
Hint 1 - reveal when you want a nudge
Treat “exactly twice” literally. CRESCENT contains two repeated letter types; list them before checking the other words.
Hint 2 - reveal when you want a nudge
C and E each occur twice in CRESCENT. C is absent from LANTERN, while E occurs there once.
Reveal the solution and explanation
The missing letter is E.
CRESCENT is C–R–E–S–C–E–N–T. Its only letters occurring exactly twice are C and E. That one statement reduces the alphabet to two candidates, without requiring a guess about the lantern keeper’s sign.
LANTERN is L–A–N–T–E–R–N. It contains E once and C zero times, so only E survives the first statement. The two N characters are worth noticing: N cannot qualify as a once-occurring letter there, although it occurs in both of the first two words.
Finally, LIGHT contains no E, satisfying the third statement. It contains no C either, but C has already failed the LANTERN requirement. A clue’s failure to distinguish two candidates by itself does not make it untrue or useless as a check.
Counting all 26 possible letters against all three requirements gives exactly one survivor. No pronunciation judgment is needed: the answer follows from finite character counts. Inserting another letter because it makes a more appealing sign would change the stated task.
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