Hi Karthi,
Tou can try this code and check solution...
PARAMETERS: INNER TYPE I.
data n type i.
n = inner.
DO INNER TIMES.
DO n TIMES.
WRITE: '+'.
ENDDO.
WRITE:/.
n = n - 1.
ENDDO.
In this link you can view how use arithmetic operators:
http://help.sap.com/erp2005_ehp_04/helpdata/en/fc/eb32e2358411d1829f0000e829fbfe/content.htm
Regards,