Excellent, I’m pleased you got this sorted!
You’d need to enter 24 for the bottles. Breww will not multiply by the number of bottles for you automatically. Doing this way means that you could add the 24 bottles, but you could also (for example), add one cardboard box.
If you have a container type of 350ml bottle and always use the same stock item bottle for this (e.g. you have a single 350ml bottle, and they’re not printed with different beer brands on them), then you could add the bottle as a stock item to the container type instead of setting it on each individual product. This should save you time as it will be, in effect, automatically added to all products using a 350ml bottle and in the correct quantity automatically (24 in this case).
To do this, go to the Containers section of Breww and edit the 350ml bottle and add the stock item in the “Default packaging stock items” section. There’s more info on this here.
I hope this helps 