sufficient next extent space

I have an SQL script that looks for sufficient space for the next extent. I am having a problem though when Oracle is breaking the datafile into multiple free extents, i.e.  

26  107,758    153,816 ***FREE***
 426  126,985    507,904 ***FREE***
 426  190,473    421,824 ***FREE***
 427        9    507,904 ***FREE***
 427   63,497    507,904 ***FREE***
 427  126,985    507,904 ***FREE***
 427  190,473    421,824 ***FREE***
 

File 427 is a brand new 1900M datafile in the tablespace. Right now I am seeing the largest free as 507,904 bytes and not 1900 M. Any suggestions on how to combine the extents in the sql script.    

Jeffrey Beckstrom
Database Administrator
Greater Cleveland Regional Transit Authority 1240 W. 6th Street
Cleveland, Ohio 44113

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