SQL & PL/SQL

DB version:11.2

How can I create rougly 100mb of test data in a table using minum number of records.
If I use the below FOR loop. It takes 100,000 records to populate just 2mb.

SQL> create table a2 (mynum1 number, mynum2 number);

Table created.

begin
for i in 1..100000 loop
    insert into a2 values(i,i*2);
end loop;
end;


select segment_name, bytes/1024/1024 MB from dba_segments where segment_name = 'A2' AND owner='SCOTT'


SEGMENT  BYTES/1024/1024
-------- ---------------
A2                     2