performing calculations from internal table

hi folks,

I have the question. Here is the code..

types: begin of balfw,

kunnr type bseg-kunnr,

zuonr type bseg-zuonr,

wrbtr type bseg-wrbtr,

types: end of balfw.

data: balfwitab type standard table of balfw

with header line.

zbalanceamount type bseg-wrbtr.

select kunnr zuonr wrbtr into table balfwitab

where bseg-kunnr = p_custid.

if bseg-kunnr = bseg-zuonr.

loop balfwitab into bwa

move bwa-wrbtr into zbalanceamount.

....

I will have to read the data from the field 'wrbtr' -amount field(currency data type) from the itab

and need to add each value as I loop each time and store it in a separate variable .

Then I need to save that data into a separate variable of char type because I need to insert this data into another itable where this field is of character data type.

How can I do this?

Thanks in advance

Santhosh