Houston Texans journeyman quarterback Ryan Fitzpatrick graduated from Harvard. After a career-best day in which he threw six touchdown passes, in his postgame press conference Fitzpatrick was more interested in showing off the brain on his eight-year-old son Brady (jump ahead to the 35-second mark):
The kid is clearly a math wiz, but the problem was not actually as near-impossible to solve as most people might think. While it does require some quick addition and multiplication, it's also a trick--one I'm sure Fitzpatrick and his son have spent some time practicing.
With the premise that both numbers be in the 90s, Brady knows right off the bat that he's starting at 8100 (90 x 90). Since he was given 93 and 97, he can then just add 3 + 7 to get 10, multiply it by 90, then add that 900 to 8100 for an even 9000. All that's left is the 3 x 7 for an additional 21, and there you have it, 9021.
Yes, it's very impressive for an eight-year-old kid to calculate all that in his head in only a few seconds. But it is also something humans are more capable of doing than they might realize.