HP 50g Graphing Calculator - Manual (Page 230)

Page 6-24
Solve for F, and press to return to normal calculator display. The solution is F :
6.67259E-15_N, or F = 6.67259
×10 -15
N.
Different ways to enter equations into EQ
In all the examples shown above we have entered the equation to be solved
directly into variable EQ before activating the numerical solver. You can
actually type the equation to be solved directly into the solver after activating it
by editing the contents of the EQ field in the numerical solver input form. If
variable EQ has not been defined previously, when you launch the numerical
solver (‚Ï
@@OK@@), the EQ field will be highlighted:
At this point you can either type a new equation by pressing @EDIT. You will be
provided with a set of apostrophes so that you can type the expression between
them:
Note: When using units in the numerical solver make sure that all the variables
have the proper units, that the units are compatible, and that the equation is
dimensionally homogeneous.