When I was in high school in the late 70s, I had a Casio music calculator somewhat bigger than the one in the article, layed out horizontally instead of vertically, but probably had similar musical capabilities.

I found that by entering a number, I think it was 951, and taking the square root, it would play a melody that ended on an up note, and taking the square root again ended on a resolution note. So I could press on a special key to play a little melody! (further square roots were random and less musical)

I knew about Kraftwerk at that point (Autobahn and Radio Activity), but this was a couple years before Computer World came out. Now I wish I still had that thing!