PHILADELPHIA — A few years ago, Dennis DeTurck, an award-winning professor of mathematics at the University of Pennsylvania, stood at an outdoor podium on campus and proclaimed, "Down with fractions!"

"Fractions have had their day, being useful for by-hand calculation," DeTurck said as part of a 60-second lecture series. "But in this digital age, they're as obsolete as Roman numerals are."

The speech started a firestorm, particularly after the university posted it online.

"There were blogs and rants, and there were some critical e-mails," said DeTurck, who is now dean of the college of arts and sciences at Penn. "They'd always boil down to: 'What would we do in cooking and carpentry?' "

DeTurck is stirring the pot again, this time in a book scheduled to be published this year. Not only does he favor the teaching of decimals over fractions to elementary school students, he's also taking on long division, the calculation of square roots and by-hand multiplication of long numbers.