The scene
Mathematics museum · Sample roomA numbered object disappears from the museum’s sample room. Its teaching lock was programmed that morning to accept only cards with odd numbers.
Three assistants carried different cards, and nobody else entered the area. There is no password to guess: simply check which card could satisfy the active rule.
What we know for certain
One of the three assistants opened the room with their own card and removed the object. There were no loans, forced openings or program changes. In this case, odd numbers end in 1, 3, 5, 7 or 9. No other final digits are accepted.
The three accounts
Luna Ríos
Assistant«My card was number fourteen.»
Marco Vidal
Assistant«I had twenty-five, but I did not take the object.»
Nerea Sol
Assistant«I used my usual card, thirty-two.»
Examine the evidence
0 of 5 openedOpening these five clues does not cost points.
01The active rule
The door record confirms that it accepted only odd numbers throughout the disappearance interval.
02Luna’s card
Reception gave Luna card 14 and checked that she returned it unchanged.
03Marco’s card
Marco’s card had the number 25 both printed and encoded on it.
04Nerea’s card
Nerea received and returned card 32. She had no other enabled card.
05The intact door
The mechanism recorded one valid opening, without manual intervention. The cards stayed with their respective holders.