We keep the key to our holiday cottage in a four-digit key safe by the door. Because of my poor eyesight, I move only one of the digit rotors when I leave, so it is easier to open next time. Most visitors rotate all rotors on leaving. Is my behaviour riskier?
Joie Richards, By email, no address supplied
We pay £25 for every answer published in New Scientist. To answer this question – or ask a new one – email lastword@newscientist.com.
Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve…
