New Delhi, July 17 -- Optical illusions are a great way to examine your vision and put your observation abilities to the test. One challenge that is popular right now tests your abilities to locate the number 7F8 concealed within a grid packed with 7E8s. You have just seven seconds to find the answer to this optical illusion. Keep in mind that this challenge can be difficult to solve. It will test your brain to the limit.

Also read: Optical illusion challenge: You have a sharp IQ if you can spot 5131 among 5151 in just 5 seconds

These visual puzzles are entertaining and challenging at the same time. When we give a quick glance at something, we often presume what we observe instead of examining every single detail. This is why noticing s...