Well, this percentage of the brain thing is completely discarted by science, we are all using 100% of our brain, all the times, even when we are sleeping XD

Maybe it was never a thing in the first place

Yeah, I guess it was from a theory from a weird person or whatever, and then the sci-fi movies used it as a plot device (cof cof Lucy)

It actually depends on which parts of the brain are activated. The idea that humans only use ten percent of their brain is also a fabrication. If you think about it, the ability to see, read and interpret these sentences requires you to use multiple parts of your brain.

The 10% thing is a myth.