Source:@blatherwick_sam
Three of the many possible solutions:
"I was just guessing at numbers and figures Pulling your puzzles apart" [Coldplay]
Mathematics, geometry, perception.
— Cliff Pickover (@pickover) June 29, 2022
Using your eyes only, is it possible to determine which one consists of a single piece of rope that has its ends joined?
(Or is the task too stressful for your visual system?) pic.twitter.com/s9XkaVNCqz