NOI calculation problems

[Gerardo Lewis]

Hey guys I have prospective multi family property in Gainesville, Florida that I'm having trouble with calculating the NOI to get the cap rate so I can get an idea of how much to offer the owner when I get in touch with them. I'd like to have most or all of the info I can have before speaking to them because this will be my first time trying to get owner financing. Do more experienced investors have any tips for finding that info or is that something I can only get from the owners? With that being said too what if I run into a situation where they don't keep track of the finances like that?