1. Most recent cost is updated each time you purchase the item.

2. Date shows the date of the last time the Most recent Cost changed.

3. The calculation for average cost depends on the costing method. Moving average is obvious, the FIFO and LIFO are not.

Say you buy 10 items at $1.00 each. The first costing bucket shows $10 and 10 Items.

Then you buy 5 more at $1.10 each. The second conwsting bucket shows $5.50 and 5 items,

Overall you would have 15 items at a total cost of $155 or $1.03 each.

Now if you sell 12, the first 10 cost $10 total and the next two cost $2.20 total for a cost of $12.20 or about 1.02 each. Left in stock are 3 items at a total cost of $3.30 or $1.10 each.

There are 5 buckets, tracked separately.

If you drive your quantity on hand below zero, you will -- in every inventory system I have seen -- totally mess up the cost calculations.