I get confused and don't understand when using the FIFO first in first out method.
I see the last goods available for sale is used in Calucalating cost of ending inventory, but where do these other figures come from? The figures are always changing and I can't keep up. I don't understand how to calculate these figures from each purchased date. They are different than the figures for those dates in my book. Can you take me through each step and show me how these figures change per date of each purchase?

I hope I ask this question right, I am so confused, please enlighten me!

I don't know what you mean by the "other figures."

The only number that changes is the price. I don't know what you mean that you can't "keep up." The price changing is the entire point of using a costing method. If the cost didn't change, you could use the same cost for when you sell and for ending inventory and there would be no need for a costing method.

What is different than what is in the book? You're not saying specifically what you're referring to and talking in circles.

Let's say you had the following three purchases:
10 @ $10 = $100
15 @ $11 = $165
15 @ $12 = $180

So you have a total of 40 units and let's say you sell 30 of them. FIFO says you're using the costs of the first ones you purchased, and that would be the $10 ones. So you use the $10 for 10 of them. (Which is $100 total.) Then you move to the next price category, which is the $11 ones. So we'll use the $11 for the next 15 units.

So far we have 25 units with total cost of $265. Since we sold 30 units, we need to grab 5 more of them. So we go to the next price category, the $12 ones. But we only need 5 more, so we'll only use 5 of the $12 ones, giving us $60 more.

So that's $325 total cost for the ones we sold, that is, that's your COGS.

That leaves us with 10 units left over, at a cost of $12 each. Total value $120. That is your ending inventory.