Brain teasers are an excellent way to test out your observational skills and help you focus better. So if you've started the week off struggling to concentrate at work, then this puzzle could be exactly what you need to get you back on track.
Not only do they aid your focus, but they're also great at testing your problem solving abilities - and sharing them with family and friends is ideal for a bit of healthy competition to see who can solve it the fastest.
The Mirror reports that JagranJosh has recently shared a tricky brain teaser that challenges you to try to identify a hidden letter among the Xs and Ks.
If that doesn't sound like it'll be difficult enough, there's also a time limit of 13 seconds - and it's said that only people with "high IQ's" can crack the puzzle in that amount of time. In the brain teaser, there are five rows of Xs and Ks, and you'll need to scan all the rows and columns quickly to be able to find the answer.
Can you find the odd letter within the time limit? If you need help, you can see the answer below – but stop scrolling unless you want spoilers.
If you want to try your hand at another brain teaser, why not take a look at this one that challenges you to find the hidden giraffe amongst the other toy animals? Or, this tricky illusion tests how high your IQ is by encouraging you to spot the hidden ballerina in an image full of flamingos.
And for something to really get your head spinning, take a look at this optical illusion that appears to move the longer that you stare at it.
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