Two Chinese school pupils made waves on national television with their mental arithmetic skills, adding up 100 three-digit numbers within 45 seconds. Victorious schoolmates Wu Yaqi and Pan Yuying, both 11 and from central China, had the correct answers after random numbers were given to them one-by-one in the latest episode of Challenge the Impossible aired by state broadcaster CCTV on Sunday evening. Beside the two schoolfriends, Ren Chao and Liu Hang – both aged 12 – stood on stage to meet the “challenge to both human hearing and calculation”, according to the show’s producers. Chao and Hang did not manage to get the exact sum, but both had the first two digits of the calculation correct. The four youngsters, winners in national or world competitions, used a calculation method based on the Chinese abacus, a device that was added to the World Intangible Cultural Heritage list in 2013. A tool that enabled centuries of Chinese mathematical practice, the abacus is a popular course for schoolchildren in Chinese-speaking regions and in South Korea and Japan. The Chinese introduced abacus and mental arithmetic in the late 20th century to help solve extremely complicated calculations within a short time based on the visualisation of the abacus. Unesco adds Chinese abacus to World Intangible Cultural Heritage list “It gives me confidence,” said Chao, from Zhangjiakou in Hebei province, when asked what else the abacus and mental arithmetic gave him besides the ability to solve number problems. The three girls – from Liuyang in Hunan province – have been in training since they were six, and Hang won first place in last year’s competition held by the World Association of Abacus and Mental Arithmetic, their teacher Hu Ping said. Their rapid mental calculations sparked heated debate on social media, with many questioning if it was worthwhile investing resources in building “human calculators”. “Their parents spent so many years just cultivating a person that is the same as a 10 yuan (US$1.49) calculator – a calculator that is not always accurate. This is crazy,” said one user on Weibo, China’s Twitter-like platform. But many disagreed and said the goal of learning was beyond the use of numbers in shopping malls. “To people who said ‘what’s the point of doing such mathematics now that we have calculators’, you probably believe that calculators are a gift to humans from god, don’t you?” one said. “They surely have extraordinary concentration and capacity of thinking that you and I can never achieve. They think faster than you can use a calculator,” he wrote.