I started using an HP-48G too in the last year of primary school. When my secondary school forbade graphical calculators, I switched to a HP-15C that my dad had

I started using an HP-48G too in the last year of primary school. When my secondary school forbade graphical calculators, I switched to a HP-15C that my dad had bought for his PhD in the early 80s. Fellow students used to make fun of RPN, a calculator without = sign was mindblowing for them. I finished the university entrance math test in 12 min. This was mid 2000s. Lots of nasty calculations. Graphical calculators were banned too. They naively thought non-graphical calculators can't do numerical linear algebra or analysis. But a 15C is one of a kind. Second hand units are still crazy expensive.