Salt and Mineral (SAM) began 2024 with 330 units of its one product. These units were purchased near the end of 2023 for $20 each. During the month of January, 165 units were purchased on January 8 for $23 each and another 330 units were purchased on January 19 for $25 each. Sales of 170 units and 230 units were made on January 10 and January 25, respectively. There were 425 units on hand at the end of the month. SAM uses a periodic inventory system