For me it was learning Fortran IV (after Focal then Basic - PDP-8i) because my dad let me use his account on the uni CDC 6400 - basically built basic bigint math library that I then put to use to determine if 1000! + 1 was prime :-)
From memory, "I don't recall" - it was 50yrs ago :-) Though wolfram alpha tells me "nope,it ain't"
Though I do have some recollection of hitting account limits on compute time on the CDC machine. My dad never mentioned any overages though. He was working in CDC assembler building a simulator for something with the odd name (at the time) of a "microcontroller". It was a profs project that needed an emulator so that was his term project.
