What percentage of our brain do we use?
We use 100% of our brain.
The idea that we only use a small percentage of our brain is a myth.
The popular media and some very influential thinkers have contributed to this misconception. Statements that humans only use a small portion of their brains have been attributed to physicist Albert Einstein and anthropologist Margaret Mead. And the advertising industry is guilty of using the idea to sell their products.
Regardless of its origin, experts in the field of neurology seem quite certain that although certain pathways in the brain may be working at different activity levels, all parts of the brain are always being used—even during sleep.
Here is a link to a page called Do We Only Use 10% of our Brain? which has more information about the topic and additional links to further research.