TOKYO (AP) _ Two Japanese researchers say they've come up with a recipe for the world's biggest piece of pi.

The two, from the University of Tokyo, claimed today that they have calculated pi, the ratio of a circle's circumference to its diameter, to 3.22 billion decimal places _ a new world record, they say.

Yasumasa Kaneda, an assistant professor at the school's computer center, and Daisuke Takahashi, a graduate student, said they broke the previous record of 2.26 billion decimal places set in 1991 by researchers at Columbia University in New York City.

Kaneda said his group used a supercomputer to calculate the number twice using two different formulas, taking 36 hours 52 minutes and 53 hours 43 minutes respectively.

Pi has an infinite number of decimal places. Such an extremely precise calculation of the figure isn't necessary for any practical scientific use, but researchers say it will contribute to improving scientific calculation methods.