On December 31, 219, why was the book value of the patented technology of Company A divided by 2?

there is no need to divide by 2. The value of a patent is not initially "calculated" by the patentee or the enterprise itself. On December 31, 219, the book value of the patented technology of Company A was "calculated" by the patentee or the enterprise itself. The money spent by the enterprise on patent research and development can be entered in the column of "management expenses", but the amount of management expenses entered can never be said to be the value of the patent right. Patent rights are generally recorded in the column of "intangible assets", or as "capital contribution" and "paid-in capital". No matter which way is recorded, the quantity and value must be obtained through an evaluation company qualified for intellectual property evaluation.