Hal Roach, the famous Irish comedian, tells the story about an Irish attendant who worked in a museum of natural history. One day a visitor, viewing the skeletal remains of a prehistoric dinosaur, asked him how old he thought those remains were. Without hesitation, the Irishman responded, “Three million and seventeen years.” The tourist was amazed at the precision of the number and asked the Irishman how he came about such a precise figure. The Irish attendant explained, “Well sir, when I started working here they told me the dinosaur was three million years old, and I have been working here 17 years.” Although the naiveté exemplified in this story is refreshing, calculations of similar convenient numbers are often made to impress, or to win an argument, or made out of sheer pomposity.