I've encountered lots of other 'ways' of expressing a sum that are different to
Sometimes people put , , , and sometimes they just put . What does this all mean?? Thanks!
... hope it's right
Also, there is a section on this in this link.
It is in 'A less than B' Chapter 2.2
Thanks PaulRS for showing me the link, and of course Krizalid and ThePerfectHacker for posting the documents.