I think 10485760 is the number of bytes allocated to this EMP segment. Part of it may not have been used at all. I mean to say.... when the first extent become full, Oracle would allocate the next extent of 5242880 bytes no matter if it needs a seconed extent for 1 row or 10 rows or 1000 rows.

So, when ever the current extent get full Oracle would allocate the next extent based on the NEXT extent value and the PCTINCREASE value.

Anybody, please correct me if I am wrong.....