I keep calculating 6410 for ending inventory but its telling me it's incorrect. Can someone please help

Required Information [The following information applies to the questions displayed below.] Sandra's Purse Boutique has the following transactions related to its top-selling Gucci purse for the month of October. Sandra's Purse Boutique uses a periodic inventory system. Unit Cost $ 890 Total Cost $ 5,340 9ee Date October 1 October 4 October 10 October 13 October 20 October 28 October 30 Units 6 4 5 3 4 4,500 Transactions Beginning inventory Sale Purchase Sale Purchase Sale Purchase 910 3,640 6 920 5,520 $19,800 2. Using FIFO, calculate ending inventory and cost of goods sold at October 31. Ending inventory Cost of goods sold