BEIJING -?A set of bamboo slips dating back more than 2,300 years were officially recognized Sunday by the Guinness Book of World Records as the world's earliest decimal calculation tool.

"The significance is that it's decimal, not duodecimal as seen in other countries. Decimal did not appear in Europe until the 15th century," said Li Xueqin, head of the Research and Conservation Center for Excavated Texts of Beijing-based Tsinghua University.

The 21 slips, crafted around 305 BC during the Warring States Period, are 43.5 centimeters long and 1.2 centimeters wide each.

When arranged together as a multiplication table, the slips can perform multiplication and division of any two whole numbers under 100 and numbers containing the fraction 0.5.

The slips have inscribed numbers and holes, where threads used to go. A user would pull the threads corresponding to numbers needed to be calculated in order to see the result.

The owner of the slips remains unknown, according to Li. "Our guess is that the tool might be used in trade, or measurement of land in the kingdom of Chu."

In July 2008, Tsinghua acquired a rare collection of 2,500 slip bamboo items from the late Warring States period, which had been smuggled out of China, including the multiplication table.