GeQo Pool Size and plan worth

Hi,
 
While trying out query executions using the geqo, I could not understand the following output.
 
The geqo paramaters are set to default values. (pool_size=0).
 
When the pool_size and the worth of the plans was displayed, the following values were obtained, irrespective of the number of relations in the query.
 
For a query with 50 relations:
GEQO selected 250 pool entries,
 best  8385954963095356800000000000000000000000000000000.00,
 midvl 8385954963095356800000000000000000000000000000000.00,
 worst 8385954963095356800000000000000000000000000000000.00.
 
For a query with 20 relations:
GEQO selected 250 pool entries,
 best  45771829382598713000.00,
 midvl 45771829382598713000.00,
 worst 45771829382598713000.00.
 
For a query with 15 relations:
GEQO selected 250 pool entries,
 best  6801044405876.81,
 midvl 6801044405876.81,
 worst 6801044405876.81.
 
Please help me understand this.
 
Regards
Swati