Storing real *large* integer values - ideas?

All,

Any ideas for representing large integer values within ORACLE7's datatypes? Say, 10 times larger than a numeric(40)... Ideas for storing values in another base, say, base(256) or base(32767) or...??? Of course, the translation to base(10) could be a pl/sql procedure but I'd like to index the value(s) because this is the unique identifier for the record.

-- 
thanks in adv,
kevin
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* K. E. Fein                      "To thy own opinions be true... *

* kfein_at_primenet.com       ..those expressed herein are but mine" *

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