There are many types of multifamily buildings to choose from. Investors need to know where to start and how many units they can afford. As an investor, you can start small or large or anywhere in between. For example: there's a 100 unit apartment building for sale in a great part of town. Seller price: $35M (hint: lots of jobs and businesses nearby). If that's too much, start with something smaller like 20-30 units.
The owner has too many properties in his/her real estate portfolio and wants to unload some of them.