“And this over here” croaked the 90 year old museum tour guide, “is a fossil 4 million and 69 years old, on it’s left you can see another fossil that’s 2 million and 69 years old.”

“Wow! That’s really fascinating,” said a fellow in the audience, “how can you age it so accurately to the year?”

“Well that’s simple” answered the old chap, “It was two million years old when I started working here 69 years ago.”