India, Aug. 6 -- Optical Illusions are a great way to train the brain and also have fun at the same time, and there is a number puzzle going viral, and it is not as easy as it looks. At first glance, it just seems like a big grid of "338" repeated again and again. But somewhere in that wall of numbers, there is one sneaky "333" hiding in plain sight. Sounds simple? It is not.

These illusions mess with the way our brains spot patterns. Your mind gets used to seeing the same thing over and over, and it starts skipping the details. So when one number is just slightly different, like a "3" instead of an "8" at the end, your eyes probably will not catch it right away.

People online are calling this a real test for your observation skills. So...