Usage of comma(, ) with 'and'

[Penny Lane]

Blue, red, yellow and green
or
Blue, red, yellow, and green

is there anyone could tell me which is correct?

[Molly]

Normally, the second example.

But look at this example:

The little cottages were painted blue, red, yellow and green, orange, and pink.

That could indicate some of the cottages were painted in two colours, i.e. yellow and green.

[Alan]

Hi Penny,

To add to what Molly has said, I have to admit I omit the comma before 'and' if the following word in the list is the last one. I base this on the assumption that 'and' is a substitute for the pause previously created by the comma(s).

Hope that makes sense!

Alan
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English as a Second Language
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[Molly]