Many Indians surely remember Shakuntala Devi from their school years, whose books their parents bought in the hope that she would inspire in their progeny a love of mathematics. How often it did so, or had the opposite effect, is hard to say. But there is no doubt that some people are born with a freakish capacity for rapid calculation. For instance, Shakuntala Devi is on record for multiplying in a mere 28 seconds two 13-digit numbers (7,686,369,774,870 x 2,465,099,745,779) picked at random. I can't even enter the two numbers in a spreadsheet that fast! And I say this as an Indian, which, as we all know, means that I am a naturally gifted mathematician.
I came across this video in which another mathemagician, Arthur Benjamin, does a few tricks before a TED audience.