Do you know your own IQ?
Better question: do you think your IQ number indicates a ceiling of sorts, a boundary beyond which your brain cannot go? This very subject is debated briskly at the moment.
Science journalist Dan Hurley got in between the people who insist you CAN expand your brain power and the skeptics--and put himself through a number of paces--for his book Smarter: The New Science of Building Brain Power.