How do you “run the numbers” on a duplex or rental property?

[Tyler Villaroman]

I am currently saving up money (about 82% of my income a month) for a down payment for my first rental property in which I plan to house hack to pay for the mortgage. In the meantime I wanted to practice finding a good deal by “running the numbers” or analyzing deals in my area so that I become familiar with the terminology, the process, and ultimately what to look for in a good deal.

I know every deal has a number that makes it work... how do I find that number for a househack rental property?

I currently reside in the San Francisco Bay Area (San Mateo County) and work as a general contractor. I also understand prices to be higher here compared to most other areas across the country, but numbers are numbers. Can anyone help?