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I would be surprised if it is more than 5 for personal use, with a dedicated password perhaps for each really important thing such as bank accounts or email, and reused passwords for things like forums. Work is a different matter, depending on what you do you might have a lot, like Dave (300!), or literally zero. I always shake my head when I see the inevitable "Worst Passwords of 20XX" article at how many really, really weak passwords people use. I can understand it to some degree, though - as with most things, people tend to get complacent if something hasn't caused them any problems. Yet.