Some tourists in the Museum of Natural History are marveling at some
dinosaur bones. One of them asks the guard, "Can you tell me how
old the dinosaur bones are?"
The guard replies, "They are 3 million, four years, and six months
"That's an awfully exact number," says the tourist. "How
do you know their age so precisely?"
The guard answers, "Well, the dinosaur bones were three million
years old when I started working here, and that was four and a half