A long-haired tortoiseshell cat called ‘Towser’ is credited with killing an estimated 28899 mice in 24 years of work as the pest control expert at the Glenturret whiskey distillery in Scotland. She holds the Guinness World Record for catching mice. – WTF Fun Facts
The same way you get any estimate!
“an estimated 28899” ?
Since the figure is complete guesswork, how did it get so specific?