Nope, it's just a way we try and fool ourselves into justifying our flock's numbers. It's a really nice fun way to totally lie to yourself. 
		
		
	
	
For example I'll use my flock.
I have 97 grown chickens right now plus about 35 chicks and over a hundred eggs in the incubator. So technically I have 97 + 35 or 132 chickens, and if you count the eggs due to hatch, that number climbs and will be over 200.
In chicken math the eggs don't count of course, because they are eggs, not chickens, therefore from over 200 just brought it down to 132. The chicks don't count because they are just chicks, so that brings it down to 97. Of these 97, 15 are rooster, everybody knows roosters don't count so now I'm down to 82 chickens. Ten of these are bantams which should only count as a half a chicken each because they are small, so now I'm down to 77 chickens. I have 18 that I'm going to trade off soon, so they shouldn't count should they? So now I've only got 59. Now there are 30 laying hens for sale, I'm sure they won't be here much longer so down to only 29 Chickens. 
I'm not very good at chicken math, so an expert could probably trim a few more off those numbers somehow. 
The thing is, those 29 chickens have already laid over 1200 eggs this month and ate over 900 pounds of feed.