The TI-85 also didn't have a lot of the built-in statistical functions that the TI-83 had.

I also was the one person with a TI-85 in a school of 83s. But by the time I took the statistics class I knew enough BASIC to write my own programs to replicate the functionality that was missing.

I was a self taught TI-Basic programmer and ran into the 26 variable limit on a choose-your-own-adventure style game I wrote. I ended up breaking it into 3 programs so I had enough variables. Programs could invoke other programs so I could navigate between states.