(adsbygoogle = window.adsbygoogle || []).push({}); So uh, i kinda figured out a math equation for how many zombies there are per round.
Not sure if anyone has posted any other type of equations, but i did do a search before i posted this.

6 + [R(R-1)] = number of zombies

R = Round number

so for instance, Round 7

6 + [7(7-1)]
6 + [7( 6 )]
6 + [ 42 ]
48

I based this info from this post:
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and sort of just started cramming away on an equation.
This is my first post and I just thought i would share some info i discovered.
Hopefully this will help anyone with any curiosity for the number of zombies for any round.
please note that this is for single player, maybe someone could help with the 2 players or more.