Change output to numerical values globally

edit

I know how to make sage to output numerical results as described in http://ask.sagemath.org/question/8150...

However is there a magic line, a global variable or something like that to make sage output the numerical result directly in the following lines?

For example I don't want to type in

n(sin(100))

to get

-0.506365641109

or

n(sqrt(pi()*2))

to get

2.50662827463100

I just want to type sin(100) or sqrt(pi()*2) to get the numerical result.