I have also avoided giving Facebook my phone number, so I was surprised one day when they correctly guessed it, only asking me to confirm. I realized later that

I have also avoided giving Facebook my phone number, so I was surprised one day when they correctly guessed it, only asking me to confirm. I realized later that this was likely due to friends uploading their address book, in which case Facebook only has to match names between friends. In Nitin’s case, maybe one of his Facebook friends knows Nitin Jaisw and has him in their address book, but with only the first name. They might not have Nitin Reddy in there at all.