[R] how to do this sum?

[GuangXing]

Hi, Everybody!
I have a big table which named table_x, and all the elements in the table is very large!
Now I want to do the summay on the talbe_x[,3].
Unfornately, I can't get the right result!
And the R give the warning messages as follow:
> sum(table_x[,3])
>[1] NA
>Warning message:
>interger overflow in sum(.);please use sum(as.numeric(.)) 
(the original upper message is Chinese,and I have translated those to English.) 	

Any one tell me how to use the as.numeric(.)?
And I want to know does R support the 64bits interger?How to do?
Pls forgive my ignorance.

Thank you in advance!			
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GuangXing
2006-06-19