I can remember my father Hansen taking me to the Sydney university Coop bookshop (then in the Transient building) and buying me a proper Hewlett-Packard scientific calculator. That was over thirty years ago — I'm not sure exactly when, but it must have been before I started uni — but the calculator still works perfectly (and I think I've only had to change the battery once).
At the time I was really disappointed that it wasn't reverse-Polish, like Hansen's own calculator. But one advantage of that has only just come to light: I've shown Helen how to use it and she can check her sums with it. (It's a relatively simple calculator by modern standards, with no graphing or symbolic algebra, but we've only got as far as 10 + 5 so far, so it could be some time before we have to deploy SageMath or Mathematica.)
Going through some of my old books, I've also found a few inscribed "H. Yee", which also works fine for Helen! (These are some of the oldest science fiction books and some of the classical literature/history.)
Helen's other major gift from her grandfather is of course her iPad.