India, Oct. 16 -- Optical illusions have a way of testing how well we see things and how quickly our brain reacts to details. A new grid puzzle has now gone viral, confusing even the sharpest eyes online. At first glance, it seems simple. But once you start looking closely, the real challenge appears.

The image shows a grid with 14 columns and nine rows filled with the number '7105'. Hidden somewhere among them is a single '7103'. Finding it sounds easy, but most people struggle to spot the difference without staring at the screen for a while.

When you first see the picture, everything looks the same. Each box appears identical, and your eyes easily get lost in the pattern. That's what makes this illusion so tricky. The constant repetit...