Just wonder how he could do it
[video=youtube;MxidMGWBqWQ]http://www.youtube.com/watch?v=MxidMGWBqWQ[/video]
Here's a little more info about him:
With English sub-title and comment
[video=youtube;gUUP-xHt__s]http://www.youtube.com/watch?v=gUUP-xHt__s[/video]
I think it is very impressive, but I think there are certain tricks and strategies that you can do to make such calculations easier.
For one thing as show in the video, to take a 16 digit number and square root it 14 times will actually produce a small range of possible answers. (9999999999999999)^(1/14) give you roughly 13.8950 and (1000000000000000)^(1/14) gives you 11.7787. One can always simply remember which range of numbers will give you answer that starts with 11, 12, and 13, then calculate the following couple of decimal places to impress the public. It would be more revealing if you get someone to calculate the answer to, say to the 7th decimal places.
In short some of these programs plays in part the audience's ingorance with numbers and scale.