Once, when Bill and I were talking about something - can't remember what - that involved an arithmetic calculation, I came up with the answer all in my head. Mildly amazed, he told me that it's because Asians have this secret way of solving math problems without pen and paper (or calculator).
According to Bil, the "Asian secret" is the pen twirl.
Hahahaha. I laughed, because I remembered that in high school a lot of people DID twirl their pens constantly. Twirl while listening to a lecture in class, twirl while idly chit-chatting in between classes, and - most importantly - twirl while thinking about answers during exams.
Unfortunately, this pen twirling thing was something I never mastered. Jealous, I thought some of my classmates were twirling wizards. That is, until I saw this...
Turn down the volume on your computer. Link found by Bill. He says this is how Asian engineers complete load calculations. LOL.