Here’s another blog comment of a former NASA engineer I found while roaming for tidbits:
While I was working at NASA-JPL during the summer of 1974, I purchased a HP-25C calculator. It was such a big deal that I was able to get one of my buddies there to engrave my name in the plastic housing to show that it was my personal property, not NASA’s. I purchased a number of scientific calculators since 1974. I keep a spare scientific calculator in my luggage now. It cost me $3.00 on sale.