New Delhi, July 24 -- Optical illusions are all about finding minute differences in an image while your brain struggles to make sense of the data it has been given. Since these brain teasers rely on how the brain interprets visual information, they know exactly which tricks to employ to give your mind a workout. Optical illusions are useful for improving cognitive functions and observation skills. Case in point- this illusion that has been going viral. The challenge focuses on finding the odd number out. You are truly eagle-eyed if you can spot the lone odd number in less than 10 seconds.

Also read: Optical illusion: This puzzle will test your observation skills to the limit. Can you find the odd word out?

To solve this brain teaser, yo...