size_clause
The size_clause lets you specify a number of bytes, kilobytes (K), megabytes (M), gigabytes (G), terabytes (T), petabytes (P), or exabytes (E) in any statement that lets you establish amounts of disk or memory space.
Use the size_clause to specify a number or multiple of bytes. If you do not specify any of the multiple abbreviations, then the integer is interpreted as bytes.
Note:
Not all multiples of bytes are appropriate in all cases, and context-sensitive limitations may apply. In the latter case, Oracle issues an error message.