My high school precalc textbook actually walked you through the process of writing a simple quadratic formula solver program. By this time, I had actually already gotten into writing TI-BASIC (as the first time I really started learning to program, failing to wrap my head around both python and C before) and I had created a slightly more complicated formula program with input sanitization and error handling, as well as a few other silly formulas. After this chapter I started passing around this program, as well as a small game I had written. These things were probably the most recognized I will ever be for my code, and I still have both programs.