New Delhi, June 26 -- Optical illusions are a sure-shot way to engage your brain and improve your cognitive functions. Be it finding the hidden object in a photo or figuring out which shapes you can find in a puzzle, these challenges inspire people to put on their thinking caps and find the solution as soon as possible. One optical illusion going viral these days invites you to figure out a specific number in an image. You will be a true puzzle master if you manage to find out the solution in 10 seconds or less.

The challenge is simple. The image before you shows a vast swatch of purple. Your challenge is to find the number 708 hidden in the image. Look closely at the photo. While the image may just seem to be a patch of purple wallpaper...