Each Friday morning I post a riddle to get you to think outside the box and exercise your brain. If you are stumped, share it with a friend or colleague and see if you can figure out the answer together.
I’ll confirm answers in the afternoon so don’t worry if you don’t see your comment posted right away. I want to give everyone a chance to guess.
This week’s brain teaser: What has no arms but can knock, and when it does you should answer?