Undo

How to interpret below output?

SQL> SELECT (UR * (UPS * DBS)) + (DBS * 24) AS "Bytes"

  2  FROM (SELECT value AS UR FROM v$parameter WHERE name = 'undo_retention'),

  3  (SELECT (SUM(undoblks)/SUM(((end_time - begin_time)*86400))) AS UPS FROM v$undostat),

  4  (select block_size as DBS from dba_tablespaces where tablespace_name=

  5  (select value from v$parameter where name = 'undo_tablespace'));

     Bytes

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1.4996E+11