How many friends do you think you need?

Researchers say that most people need 3-6 close friends. I do not know how they figured this out.
Updates
+1 y
I had 6 close friends when I was growing up. 3 were from the neighborhood and the other 3 were from where I went for vacation. Two are dead. One moved far away and two of the other ones I hardly ever see anymore. I used to have a tribe as well. Getting married and having kids tales up a lot of my time and I sort of let all these relationships lapse. It is hard to make friends when you are in your 50s.
How many friends do you think you need?
Post Opinion