sistema hexadecimal
https://www.youtube.com/watch?v=TVI2Vxd7HTY   principio basico
https://www.youtube.com/watch?v=OjN40z7kN0I    suma
https://www.youtube.com/watch?v=HaKQsJcfjYM   resta
https://www.youtube.com/watch?v=S4ux71Lgc4Y   multiplicacion
https://www.youtube.com/watch?v=FNCsWgFWWWU  division