50g

Hello,
Longtime 48gx user and now have a 50g.  though I never used 
any "advanced" functions on either calculator.  

any ways, I am now having to spend time with some resident students, 
and wish that there was a way I could store (somewhat) long 
mathematical derivations in my 50g.  I don't think the equation editor 
fits this bill (I don't want to put in variables).  

Any ideas?
Thanks,
Brad