Often called the “Father of China’s nuclear subs”, Huang Xuhua said he still has one of the abacuses that were used in the production of the craft, according to the 'Chutian Metropolis Daily newspaper'.

He said the device, known as 'suanpan', helped him and his team calculate critical data to make the submarine.

The 93-year-old led the development of the Long March-1submarine almost 60 years ago, working for the China Shipbuilding Industry Corporation.

He said the company had several abacus calculation teams that were separated into specialist sections.

Each team would work “until every section reached the same result."

The noise of the beads on the abacuses would make the buildings “rattle from dawn until dusk”, Mr Huang said.

The Chinese abacus dates back to 200BC, featuring a bamboo frame and beads that could be pushed up or down.

Zhang Jinlan, who currently works on nuclear submarines at China Shipbuilding Industry Corporation, said that today’s engineers would find it impossible to use an abacus to build submarines.

But Mr Huang said doing the calculations by hand allowed him and his team to work through challenging technical issues, managing to produce five original designs in three months.

The first Long March-1 was completed in 1970 and went into military service four years later. It was only retired from service last year, and is now housed in a naval museum in Qingdao, in eastern China’s Shandong province.

- with wires