A tourist was marvelling at the dinosaur bones at a museum. He leant over to the guard and said, “Do you happen to know how old these bones are?”
The guard nodded and replied, “They’re three million, four years and six months old.”
“Wow,” the tourist said in surprise. “That’s an awfully specific number. How do you know their age so precisely?”
The guard answered, “Well, the dinosaur bones were three million years old when I started working here and that was four and a half years ago.”