Reports & Discoverer :: Character In Excel

i create report containe employee bank account and i have to converted to excel using button in the report page table is like this

(empno number(8),
bank_acc char(23),
salary number(13,2))

it work fine but my problem is most of the account start with zero like (000000546789) in report its appear okey but when i converted to excel its appear like this(2.36098E+11)

im using procedure RPT2XLS

this is the code i used as format trigger in the field of bank_acc

RPT2XLS.put_cell(1, acc1 ,FontColor => 1, FontSize => 10);