DATA: f1(25) VALUE 'abcdef_1234567890', 
      f2(25) VALUE 'abc_1234567890', 
      g(10) TYPE c. 

PERFORM write_lastten USING f1. 
PERFORM write_lastten USING f2. 

*&---------------------------------------------------------------------* 
*&      Form  write_lastten 
*&---------------------------------------------------------------------* 
*       text 
*----------------------------------------------------------------------* 
*      -->P_F  text 
*----------------------------------------------------------------------* 
FORM write_lastten USING value(p_f). 
  DATA l_offsetforten TYPE i. 
  l_offsetforten = strlen( p_f ) - 10. 
  MOVE p_f+l_offsetforten(10) TO g. 
  WRITE:/ g. 
ENDFORM.                    " write_lastten 

Output. 
1234567890 
1234567890