As I tell students (and parents) often… buy as much RAM as you can afford. I've never had some one ever in all my years of recommending hardware tell me they bought too much RAM.
I have, however, had many come back regretfully telling me that they should have listened as they are faced with having to buy another machine within a year or so of buying their first one.
Nowadays, I recommend 16GB of RAM and 32 GB if you can afford it and are able to get it on the machine. If a person is only using it for surfing the web, I would think 8 GB would be ok. However, I just had this conversation with a colleague and this article lines up with what I told her several weeks ago. As much as you can afford. Scrimping on RAM always gets you in the end.
This also applies to school purchases of hardware.
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