Common knowledge, Why The Human use Only 10% From His Brain?

Common knowledge, why we use only 10% From Our Brain ?

our brain has the ability to do a lot of daily tasks Whatever it's easy or very hard like solve mathematics also it's the main storage for our memory although the brain doing all of this it's have more abilities we cannot use it and this because the normal human use only 10% of his brain but there are some people said that if a human used more than this 10% he will be able to control of things without touch it or his memory will be super like remember a number consists of million-digit. 

So what's the science said in this hypothesis?

this hypothesis was showed in many of documents and Dramas but there isn't a shred of evidence that prove it but this hypothesis because there are many parts in the brain don't have been used and if this parts used the human will be genius Because he will use all the advantage of his brain.

this hypothesis created at the 20 century By A group of psychologists at Harvard University By the head of the American philosopher and psychologist William James by doing an experiment to measure the IQ of some children by memorizing many mathematics equations and when the results were appeared Dr. William James  Said that the human doesn't use the full abilities of his brain and don't say the percent.

So From Where the 10% hypothesis Come From?

At 1963 The scientific community was surprised By a book written by Lowell Thomas contain a phrase said that there is a professor from Harvard University said the human use only 10% of his brain but Dr William James didn't say that and this percent is from the writer but Dr Williams said the human doesn't use the full abilities of his brain only but the reason of Lowell Thomas to say the 10 % is only to attract people to read his book.

then some people said Albert Einstein said that he was smart because he used more than 10% of his brain But this false and don't have any proof. 

So This quotation is True or False?

After doing many experiments and studies of all parts of the brain by using  Magnetic Resonance Imaging that's proved that there is no part in the brain not used and the human used 100% of his brain during all day even sleeping.
and the scientists put a map for every part in the brain and its function
But the uses of the brain differences due to the difficultly of the task like if you eating you will use a small part of your brain but if you trying to solve Mathematical problems you will use a large part of your brain but overall you will use all parts of your brain.