I can remember buying my slide rule. Dixon and Parkers in NNottingham I was 10 at the time and still at primary school. I can also remember getting my sinclair calculator about 5 years later as I did O levels. I've still got them both and I'm 66 now.

I've not got the commodore scientific calculator I got as I went to university in 1974 though. That one had trig functions(so does the slide rule) and did stats too.