When is Purchases and Merchandise Inventory Beginning credited? Please cite an example transaction. How would you extend this to the worksheet?

Depends entirely on what method you're using. Since you're using a Purchases account, it sounds like you may be doing the periodic method, something not used much anymore. It also sounds like you may be referring to doing an end-of-period adjusting entry. But you've pulled this out of context, so I'm not sure.

It also sounds a bit like a homework question. (The way it is worded is not how most people talk.) If it is, first see our guidelines about posting homework:

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