'Guesswhat' this story is about

Let's start the way the book does, with an easy question and a few hints to help solve it:

Q. How many physicists does it take to write a book?

Hint: The book is 320 pages long, including index and appendices.

Hint: The title of the book is "Guesstimation" - which, if my keyboard had more esoteric keys and gizmos, would be spelled "Gue??timation," except the question marks would be lined up like lower-case backward S's and the dots would hang below the line.

A. Two.*

Note the asterisk. For ease of reading, the footnote is inserted right here: *John Adam is a professor of applied mathematics, but his first degree is in physics. Larry Weinstein is a nuclear physicist. When I met them at Old Dominion University, where both have offices, I got there early. Weinstein was late, but when he arrived he was wearing a tie that bore a portrait of Albert Einstein, so points for style.

Now for an actual question from the actual book:

Q. How many people in the world are picking their nose right now?

Hint: You should read Chapter 1, "How to Solve Problems," before noodling this question.

A. Ten million.*

*The answer was reached by estimating that your friends spend two minutes a day picking their noses (Weinstein and Adam assume that you, like they, are not pickers yourselves). That's not important. What is important is how they reached the answer, which was by - yes - guesstimating.**

**They figured that 10 seconds is way too short, but 1,000 seconds is way too long, so they settled on 100 seconds, which is about two minutes.

Q. Why is guesstimating important?

Hint: The book's subtitle is "Solving the World's Problems on the Back of a Cocktail Napkin"

A. Major employers like to test an applicant's ability to think creatively and quickly, breaking problems down to solvable parts, so they often ask questions such as, "How many piano tuners are there in Los Angeles?" during interviews.*

*Microsoft and Smith Barney, to name two, as Weinstein and Adam do in the preface. But the authors also say it's important to be able to figure out things for yourself. For example, if someone is touting the use of corn-based ethanol as a gasoline replacement, you can calculate the pros and cons. "My car uses a lot more energy than I do," Weinstein points out. "Why would I want to put food in my gas tank? There are lots of questions like that that have to do with public policy where you can answer yourself and not have to rely on so-called experts."

Q. Such as?

A. How much land would it take to convert the U.S. to solar power? How much carbon dioxide does a coal-fired power plant release and what fraction of the mass of the atmosphere is that? What is the risk of dying in a car crash? Via shark attack? How much is a part per million? A part per billion?*

*The latter question gained significance with a recent news story about pharmaceutical drugs being found in water supplies, in parts per billion or trillion. Weinstein, with a few simple calculations (supplied in the book), compared one part per billion to lining up grains of sand along the equator, then looking for the single grain colored red.

Q. How did they get the idea for this book?

Hint: Well, just look at them.

A. Weinstein teaches a seminar called "Physics on the Back of an Envelope," which is all about estimation. Adam touched on estimation in his first book, "Mathematics in Nature: Modelling Patterns in the Natural World." That book arose from questions he would ask himself as he walked to work, such as: "I wonder how many leaves are on that tree?" They decided to collaborate on "Guesstimation," published by Princeton University Press, which recently sold the Chinese rights, leading Adam to estimate that if 1 billion Chinese buy at least two copies each, that would be spectacular.

Q. Isn't Weinstein one of the guys who orchestrates the annual pumpkin drop off the roof of a 10-story building, to see which student can apply physics principles to build the best pumpkin-catcher?

A. Yes, he is.

Q. How does guesstimating work?

Hint: Look at Page 29 and the sticky question of lining up all the pickles sold in the United States last year.

A. Weinstein and Adam recommend breaking down the problem into manageable parts: estimate the length of the average pickle, then the average number eaten. The authors suggest that the average American eats more than one pickle a year, but less than one per day, so they chose 20 as a good figure to work with.*

*"Sometimes you don't need an exact answer," Adam says. He points to pi, familiar to millions of schoolchildren as 3.14, even though it actually could be calculated to an infinite number of decimal places.

Q. How does the average person know some of the numbers needed to estimate answers, such as the population of the world?

A. They're in the handy appendix at the back of the book.

Q. Is there a reason this story is written in Q&A form?

Hint: Check the format of the book, including hints.

A. Yes, there is. But the hints are not printed upside down, as they are in the book.

Q. When will the book be published?

A. It's available now, for $19.95.

Q. How many copies will be sold?

Hint: Consider that questions asked and answered range from silly to serious, that early readers have actually used the words "wow" and "delightful."

A. A guesstimate? Lots.

Diane Tennant, (757) 446-2478, diane.tennant@pilotonline.com