Another way to know how much inserts ,delete ,update has taken in a table is by a feature called monitoring.

just give

alter table emp monitoring;
analyze table emp compute statistics;
insert 5 rows in emp;
delete 10 rows in emp;
update 5 rows in emp;

cool down for three to four hours or give a shutdown immediate then

SELECT * FROM SYS.DBA_TAB_MODIFICATIONS;

but these this has some limitations.Pls check whether it helps or not