It is said that in Ming Dynasty there was an artisan working on this pass, called Yi Kaizhan, who was good at arithmetic. As long as the materials needed were accounted by him, the accuracy and economization of material needed were available. The inspector did not believe it at all and required him to count the number of the bricks used for establishing this pass. After Yis careful account, he said there were 99,999 bricks. Afterwards, the inspector bought the bricks according to his words and ...