If the position of "gold" is (x, y), the corresponding text position is (x+ 1, y+2).
∴ The password key found is: add 1 on the abscissa and 2 on the ordinate of the corresponding text.
The position of "Zheng" is (4,2), and the corresponding letter position is (5,4), which means "Zhu".
The position of "do" is (5,6), and the corresponding letter position is (6,8), which means "you".
The position of "number" is (7,2), and the corresponding letter position is (8,4), which means "Cheng".
The position of "Xue" is (2,4), and the corresponding letter position is (3,6), which means "altogether".
The real meaning of "doing math" is: I wish you success.
So the answer is: add 1 to the abscissa and 2 to the ordinate of the corresponding text. I wish you success!