New Delhi, Oct. 4 -- A new viral optical illusion is having the internet pause and look twice. The puzzle is asking viewers to find the number 181 hidden in a big grid of 191, and players have to do it in five seconds. Many are racing against the clock to prove their observation skills.

At first glance, the image looks like a neat grid where each square has the number 191. The layout is clean and repetitive, which can confuse your eyes. Somewhere in this grid is a single square that breaks the pattern, where the number 181 is hiding among dozens of 191s.

The challenge is simple: Can you spot 181 in under five seconds? While the challenge looks simple, only a few can do it quickly. Most get stuck scanning row after row without success. I...