chinapay

http://s.yanghao.org/program/viewdetail.php?i=71959

http://www.codeproject.com/csharp/biginteger.asp

http://www.cnblogs.com/clc2008/archive/2012/03/01/2375294.html

http://www.cnblogs.com/wangchengshen/articles/3595841.html