Javascript

http://gwydir.demon.co.uk/jo/javascript/numbers.htm

http://en.wikibooks.org/wiki/JavaScript/Variables_and_Types

https://developer.mozilla.org/es/docs/Gu%C3%ADa_JavaScript_1.5/Funciones_predefinidas/Funciones_parseInt_y_parseFloat

InnerHTML

http://www.youtube.com/watch?v=JTiNndhKyz0
http://www.youtube.com/watch?v=F-GXpTe1txU
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide
https://developer.mozilla.org/en-US/docs/Web/JavaScript/A_re-introduction_to_JavaScript