I opened my first bank account when I was 17 - well actually I won a competition run by the bank for school kids and the prizes were your own bank account with .... £3 in it.... !!!! (In those days, 8 hours working in a shop on your feet all day earned you £3.59 so that was a lot

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I still have that as my main checking account nearly 35 years later (though I have a few others too to be on the safe side - not that I don't trust bankers but... )