You sound like you were at college the same years as me fall 1969 - spring 1973.
Started ME school with a cheap metal slipstick. HP35 was introduced in 1972 when I was a Junior or Senior, but who could afford a $400 calculator? That’s $2,915 in 2024 dollars! I remember I bought a cheap Casio calculator a couple years after graduating, then finally an HP 11C and a 12C in the early 80s.
We’re of the same vintage for college years, and I still have the old slide rule that served me well. Senior year I bought a Craig calculator - 4 functions with a constant key. Fortunately, the cadet store sold products at cost so I was able to afford it, about $90 as I recall.