Grant Cardone's calculation

[Joshua Hill]

Hey guys, I've been watching a good number of Grant's videos on getting started on multifamily real estate and I've noticed he does a quick calculation when he's skimming over examples of deals. It deals with the  Buying price, around 25% down payment, the cap rate and all of a sudden he has an estimate of the Income that the property could bring in.  Does anyone know specifically how he does it or know of a similar calculation?

Also, do you all have any tips on finding good/top notch brokers that will give me access to looking at the prime deals and not the left over loopnet ones?