A new optical illusion puzzle is making waves on Facebook, challenging users to put their observation skills to the test. Such visual tricks have long fascinated people by encouraging them to question ...

Here’s a famous teaser that I don’t really like much: What number comes next in the sequence 8, 5, 4, 9, 1, 7,…? It’s not so obvious. It becomes a little easier when we write the sequence in words: ...