I have slight hearing problems too. It's been a nightmare for me as I partly rely on lipreading and I haven't been able to so I've been having to ask people to repeat themselves a lot.
About 7. I require 3 for personal use (one main, 2 junk for accounts for websites that I don't care about but need an account), one school one, one for my scanners smtp scan to email function and the other 2 are just old ones.