New Delhi, July 18 -- Optical illusions and brain teasers are all the rage these days and this one is sure to test your thinking skills to the maximum. At first glance, the photo is just a wall of 40s. Rows upon rows of the number 40, copy-pasted to trick your head. But somewhere in that sea of uniformity, three numbers don't belong - and spotting them is trickier than it looks. This viral puzzle doing the rounds online is challenging viewers to "Find three different numbers." It's a classic visual bait-and-switch. The kind that forces your brain into autopilot until you suddenly realise that something is off.

Users have been sharing the image - a black background filled with white "40" blocks. Some claim they spotted the odd ones out in...