Question: reading and writing

I calculate a long polynomial p(x) where the coefficients depend on a varaiable d. That takes about 10 minutes. I put a colon at the end of the computation because the result is very large. Then I put d=12.2 say and proceed to do a lot of other things. All well and good. I save the file as fooapril23 and go home. When I return I want to repeat the computaion with d=12.5 which I can do by opening the file, saving it as fooapril24. Then I have to recalculate p which is 10 mintes wasted until I can say d=12.5 and proceed with my work..  I would like to "park" the result for p in a file somewhere and then import it when needed. I went to the read and writeto help pages but could not understand it at all. (I tried bit when I did the writeto command and then opened a new worksheet and tried to read I got an error:

Error, on line %1, syntax error, `>` unexpected:

(The > was the Maple prompt I guess.)

I have tried over the years to use the writeto and read commands but I think the help pages are written for unix gurus and I am a Mac user.

BTW I am using Maple 2026 My worksheet starts with > restart; Digits:=20: with(Plots):
I guess requiring the with(Plots): command in 2026 is some kind of an in joke?