楚简《九九术》出土！乘法口诀2300多年前就有了

战国时期人们如何计数？出土简牍如何修复释读？记者从湖北省文化和旅游厅了解到，湖北荆州秦家咀墓地出土的乘法口诀实物——楚简《九九术》，较此前所知最早的湖南里耶秦简乘法口诀《九九表》，时间要早约一个世纪。

The mathematic formula, written on a piece of bamboo slip, was unearthed from a tomb in the city of Jingzhou, central China's Hubei province.

The formula, which dates back to the 4th century BC during the Warring State Period (475-221 BC), precedes another piece discovered in central Hunan province by approximately a century, said Yang Kaiyong, the leading archaeologist of the tomb's excavation project.

秦家咀M1093墓葬出土的楚简盛于竹笥内

图源：荆州博物馆

Scientists have used infrared scanning to reveal the words on the slip as "five times seven is thirty plus five, four times seven is twenty plus eight, three times seven is twenty plus one."

Tan Jingnan, a historian with Jianghan University, said the pithy multiplication formula was already popular during the Warring State Period when Chinese government officials used it to calculate production and properties figures.

Thousands of bamboo slips holding over 30,000 characters ranging from mathematics, literature, and animal husbandry to medicines have been discovered in the tomb.

来源：新华社