Older school.
HP-41C and HP-41CV.
One thing I really loved - at the time, Engineering Economy had a BUNCH of interest rate tables in the back of the book that you were expected to use for just about everything, all the homework problem. I programmed up all the standard functions and nailed everything to 6-8 significant digits, never looked at the tables. Never did have anyone try to call me on sig digits, which would have been a loser for the TA.
And then there were problems where they expected you to iterate for an interest rate. Except I could write the problem into a formula, then use a Solve function to do the iteration, and again, give an answer to 6-8 significant digits. Loved that stuff.