conversion function to_char to_number

SELECT
'['|| to_char(325)||']',
'['|| to_char(12325,'9,999.999')||']',
'['|| to_char(12325,'99,999.999')||']',
'['|| to_char(12325,'fm99,999.999')||']',
'['|| to_char(0.25)||']',
'['|| to_char(0.25,'00.99')||']',
'['|| to_char(10.25,'00.99')||']',
'['|| to_char(1325,'')||']',
'['|| to_char(-1325,'9,999')||']',
'['|| to_char(325,'fm9,999')||']',
to_char(sysdate,'day'),
to_char(sysdate,'month'),
to_char(sysdate,'mm-dd-yyyy hh24:mi:ss'),
to_date('','yyyymmdd')
FROM dual;

'['||TO_CHAR(325)||']' '['||TO_CHAR(12325,'9,999.999')||']' '['||TO_CHAR(12325,'99,999.999')||']' '['||TO_CHAR(12325,'FM99,999.999')||']' '['||TO_CHAR(0.25)||']' '['||TO_CHAR(0.25,'00.99')||']' '['||TO_CHAR(10.25,'00.99')||']' '['||TO_CHAR(1325,'')||']' '['||TO_CHAR(-1325,'9,999')||']' '['||TO_CHAR(325,'FM9,999')||']' TO_CHAR(SYSDATE,'DAY')               TO_CHAR(SYSDATE,'MONTH')             TO_CHAR(SYSDATE,'MM-DD-YYYYHH24:MI:SS') TO_DATE('','YYYYMMDD')
---------------------- ------------------------------------ ------------------------------------- --------------------------------------- ----------------------- ------------------------------- -------------------------------- ----------------------------- -------------------------------- -------------------------------- ------------------------------------ ------------------------------------ --------------------------------------- ------------------------------
[]                  [##########]                         [ 12,325.000]                         [12,325.]                               [.25]                   [ 00.25]                        [ 10.25]                         [####]                        [-1,325]                         []                            monday                               september                            09-03-2018 10:34:20                     02-SEP-18