i have just installed a new Office 2013 recently and i encountered this problem in excel:
when i put a Sum formula at the end of a column, it will add up all the values in that column, but when i add in a new value, or change a value, the sum at the end column do not change automatically ie it does not add up to the new total again. why? it does not happen when i used the old system last time.

Hi
are calculations set to automatic?

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how to check whether it is automatic?

I don't know about 2013 but in 2010 it was somewhere in the Options ( haven't got it right here)
Anyway, if you hit F9 and the cell calculates, it means that calculations are set to manual

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