Oracle Database Discussions

hi guys,

select
s.username  
,s.sid  
,s.serial#  
,s.osuser  
,s.logon_time  
,s.status  
,s.machine  
,t.used_ublk  
,t.used_ublk*16384/1024/1024 undo_usage_mb  
from v$session     s  
    ,v$transaction t  
where t.addr = s.taddr; 

My question is do i have to multiple base on the parameter below?

SQL> show parameter block

NAME                                 TYPE        VALUE
------------------------------------ ----------- ----------------------------
db_block_buffers                     integer     0
db_block_checking                    string      FALSE
db_block_checksum                    string      TYPICAL
*db_block_size                        integer     8192*
db_file_multiblock_read_count        integer     128

in these case i should -> t.used_ublk*8192/1024/1024 undo_usage_mb ??