Due to the large volume of book wholesale business and low price, the weighted average method at the end of the month is the most suitable method to calculate the cost.

Suppose there is 2 1 book at the beginning of the month, and the cost is 105 yuan. I bought 1000 copies for 2000 yuan this month. 900 copies have been sold this month, and now you want the remaining inventory cost.

Then using the weighted average, the unit cost of this month's delivery = (2000+105)/(1000+21) = 2.0617, so the book selling cost this month = 2.0617. Month-end inventory = 21+1000-900 =121,and month-end inventory cost =105+2000-1855.53 =.