If Dava Sobel's Galileo's Daughter —which, after a long run as a bestselling hardcover from Walker & Co., has occupied a place on the paperback list for six months in its Penguin edition—is any indication, literary nonfiction plus math equals sales.

Several math-related titles have found success, à la Sobel, perhaps making it a bit of a trend but not an entirely new idea. For instance, back in 1884, under the ironic pseudonym A. Square, author Edwin A. Abbott satirized class distinctions in Victorian England via a two-dimensional world inhabited by geometric shapes, and demonstrated the social implications of math. Flatland, an amalgam of math and science fiction, has never gone out of print. Nine editions of Flatland are available, ranging from a pocket-size version from Shambhala Publications to G.K. Hall's large-print edition. Penguin executive editor Michael Millman said Flatland continues to be a slow but steady seller. "Penguin has had Flatland on its list since the '70s, and it has recently been moved into Penguin Classics," he noted.

More than 100 years after publication, Flatland has inspired writers to attempt sequels to Abbott's satirical story. The latest sequel, by Ian Stewart, is called Flatterland and is to be published by Perseus next month. Stewart, a mathematician at Warwick University in England (and author of more than 60 books, including Does God Play Dice?) said the idea of entering other dimensions only hinted at in Flatland prompted him to push things further. Flatterland features Victoria Line, an Internet-savvy Flatlander who gets caught up in the third dimension. With an assist from Superpaws (Schrodinger's cat), the Space Girls and the Hawk King (a nod to Stephen Hawking), Victoria, the thoroughly modern granddaughter of A. Square, explores quantum mechanics, black holes and superstrings.

Stewart, who first read Flatland when he was an 18-year-old student at Churchill College Cambridge, recalled being impressed by the fact that it is so unique, or as he put it, "a genuine once-off." He said he had never read anything like it before. "There are resonances with Swift and Carroll, but it's more gentle than Gulliver and not at all like Alice," he told PW. "The main books that come close are, like mine, deliberate imitations or sequels." Other recent sequels include Sphereland: A Fantasy About Curved Spheres and an Expanding Universe by Dionys Burger (available only in a two-in-one volume with Flatland, from HarperCollins) and The Planiverse: Computer Contact with a Two-Dimensional World by A.K. Dewdney (Copernicus).

Given the unique nature of Flatterland, v-p/associate publisher and marketing director Elizabeth Carduff said the house plans to launch with a 20,000-copy first printing and a similarly unique marketing campaign. "I think what's special is we're trying to get to all the sci-fi and mathematical communities on the Web," noted Carduff. The print ad campaign is expected to range from the Scientific American to the New Yorker.

Science fiction and technical bookstores are already gearing up for the latest Flatland sequel. "Older readers especially will be intrigued by Flatterland," said Willie Siros, owner of Adventures in Crime and Space in Austin, Tex. "Flatland used to be required reading in geometry; it's a classic."

At Quantum Books in Cambridge, Mass., Nick Moscato said, "When there's an oddball title like that, we put it up front near the register and see what happens. "We did backorder some Flatland, and we will put them together."

Perseus senior editor Amanda Cook has such high hopes for Flatterland that she's already signed Stewart for another book. "I was amazed to find there has never been an annotated edition of Flatland," she told PW. Booksellers can expect Stewart's annotated version from Perseus as a paperback original this winter.

Among the publishers that have recently tested the math and social criticism sales connection is the Boston-based Beacon Press. In February, Beacon published Radical Equations: Math Literacy and Civil Rights by Robert P. Moses and Charles E. Cobb Jr. With the help of Cobb, a journalist, Moses, the founder of the Algebra Project and a long-time civil rights activist, argues that since students' performance in algebra determines whether they will get onto the pre-college track, math literacy is crucial to civil rights. Already in its third printing, Beacon director of publicity Pamela MacColl characterized Radical Equations as "one of the better selling books of the season."

According to Beacon education editor Andrew Hrycyna, who signed the book and was a student of Moses, "What makes Radical Equations fascinating is that it makes the intellectual political. Moses ties the work he did registering sharecroppers to vote [in the '60s] with his work now. He was fighting before for political enfranchisement; now he's fighting for economic enfranchisement."

On the lighter side of math, next month Walker Publishing releases its new Wooden Books gift line that publisher George Gibson said "makes knowledge accessible." Gibson attributes much of the appeal of the current wave of math books to their interdisciplinary nature. "They're not dry math texts," he explained. The first Wooden Books are Matthew Watkins's Mathematical and Physical Formulae, Miranda Lundy's Sacred Geometry and Robin Heath's Sun, Moon & Earth. Each book is 64 pages long and slightly smaller than the standard 6"×9" format.

If these Walker, Beacon and Perseus releases are any indication, it looks like the new math offers a solid formula for old-fashioned book sales.