The Math Behind Overpopulation

One unaltered* cat will have a litter every 8 months. Each litter will contain between 4-6 kittens, half male and half female.
*unaltered: a cat who has not been spayed or neutered
Sheila is a feral female cat, at 8 months old she has her first litter
8 Months Later
Sheila has her second litter
Meanwhile the 1st litter has their first litter
Another 8 Months Later
Sheila has her third litter
The 1st litter has their second litter
The 2nd litter has their first litter
The Results
44 feral cats have been born in 16 months.
Sheila now has 12 children, 16 grandchildren, and 16 great grand children.
*this is based on an average female feral cat, actual results may vary*