The answer to last week’s challenge is. Q:How can you tie a knot in a piece of string without letting go of either end?

A: Pick up the string with both arms folded and then unfold your arms.

This week’s Mental Floss challenge is.

Q: There are three light switches in a room. You can do what you want with them and then go into the next room where there are three light bulbs. How can you identify the switch that turns on each of the lights? You can’t go back into the room with the switches. The wall between the rooms are sealed and the door locks behind you when you go into the second room.

The answer along with another challenge will appear next week.

Have a great weekend!