Li Chang with his wife Zhang Guiqin shows the German mechanical calculator at his home in Taiyuan, capital of north China's Shanxi Province, Oct. 21, 2015. Retired Chinese engineer Li Chang, an extensive collector in antique mechanic products, is now planning to raise fund on the internet to realize a promise he made to his wife. Li Chang married his wife, Zhang Guiqin, in 1958 and he made the promise at their golden wedding anniversary. Li Chang owns a WWII German Brunsvigr mechanical calculator which is in good condition. Recently, Li Chang posted an advertisement to sell the calculator through Wechat, one of China's most popular mobile social apps, and hopes to raise enough money to bring his wife to the long-awaited promised tour around Europe. (Xinhua/Yan Yan)
