You could even say "If it's not cleaned and sanitary, I will hire a cleaner, and charge you directly.   

While doing back of the napkin due diligence what is a standout factor that will immediately turn you away from analyzing the deal any further?

Is there some rule of thumb/back-of-napkin easy way to guesstimate typical the difference?

Not sure of your definition of the stock market so will stop there.2)  back of napkin calculation  Option A take current balance of your 401k and make assumption on your compound annual return until 59.5. 

It has been taught for "quick analysis" or "back of the napkin analysis" by many different real estate investors for decades, long before you started investing.

They will not accept things such as paper diapers, sanitary napkins, tampons, wads of toilet paper, balls of hair, grease, oil, table scraps, clothing, rags, sand, dirt, rocks, newspapers, cosmetics containers, or children's toys.

Johnson can share with you my biz model on a paper napkin when you attend his next meet-up.

Is this just a verbal or napkin agreement i make with the family member and it just gets done (surely not), or is this something that gets lawyer-ed to death and recorded in the public records?  

Any half-wit can take a basic business law class and write up an enforceable and legal contract on a fast food napkin.

@Guy Gimenez can you give me some back-of-the-napkin math on what a deal with existing financing in place would look like?