Count the number of "F"s in the following sentence.

Scroll down once you have completed counting.

How many did you count? Three ? Four?

The answer is Six.

One reason you may have missed counting all Six is your brain does not process the "F" in "OF". The word is pronounced "OV".

Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a total mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.

Try this exercise. It will really make you wonder how your brain works: While sitting at your desk, lift your right foot off the floor and make clockwise circles. Now, while doing this, draw the number "6" in the air with your right hand. Your foot will change direction and there's nothing you can do about it.