file down load to the prsentation server in to spread sheet

Hi i am downloading a internal table using class CALL METHOD cl_gui_frontend_services=>file_save_dialog.

But while downloading it is giving exponential format.when i am changing the format but then it is giving wrong values

Example : my internal table is having a field called EXIDV -data element of EXIDV(char 20).in the internal table it is having values of 376543212000003219 but in the spread sheet it is comming 376543212000003000(after changing the format)

Is it case for long data element.but i am having fields more than 30 char length and those are down loaded properly

Please need your help

With thanks and regards,

Durga.