--===== Return all characters that ISNUMERIC thinks is numeric
     -- (uses values 0-255 from the undocumented spt_Values table
     -- instead of a loop from 0-255)
 SELECT [Ascii Code]        = STR(Number),
        [Ascii Character]   = CHAR(Number),
        [Standalone] = ISNUMERIC(CHAR(Number)),
        [CharZero] = ISNUMERIC(CHAR(Number)+'0'),
        [ZeroCharZero] = ISNUMERIC('0'+CHAR(Number)+'0'),
        [ZeroCharCharZero] = ISNUMERIC('0'+CHAR(Number)+CHAR(Number)+'0'),
        [ZeroChar] = ISNUMERIC('0'+CHAR(Number))
   FROM Master.dbo.spt_Values
  WHERE Type = 'P'
    AND Number BETWEEN 0 AND 255
    AND (ISNUMERIC(CHAR(Number)) = 1
       or 1 = ISNUMERIC(CHAR(Number)+'0')
       or 1 = ISNUMERIC('0'+CHAR(Number)+'0')
       or 1 = ISNUMERIC('0'+CHAR(Number))
        )

Ascii Code Character Standalone  CharZero    ZeroCharZero ZeroCharCharZero ZeroChar
---------- --------- ----------- ----------- ------------ ---------------- -----------
         0           0           0           1            1                1
         9           1           1           0            0                0
        10           1           1           0            0                0
        11          1           0           0            0                1
        12          1           0           0            0                1
        13           1           1           0            0                0
        32           0           1           0            0                1
        36 $         1           1           0            0                0
        43 +         1           1           0            0                0
        44 ,         1           1           1            1                1
        45 -         1           1           0            0                0
        46 .         1           1           1            0                1
        48 0         1           1           1            1                1
        49 1         1           1           1            1                1
        50 2         1           1           1            1                1
        51 3         1           1           1            1                1
        52 4         1           1           1            1                1
        53 5         1           1           1            1                1
        54 6         1           1           1            1                1
        55 7         1           1           1            1                1
        56 8         1           1           1            1                1
        57 9         1           1           1            1                1
        68 D         0           0           1            0                0
        69 E         0           0           1            0                0
        92 \         1           1           0            0                0
       100 d         0           0           1            0                0
       101 e         0           0           1            0                0
       128 €         1           1           0            0                0
       160           1           0           0            0                1
       162 ¢         1           1           0            0                0
       163 £         1           1           0            0                0
       164 ¤         1           1           0            0                0
       165 ¥         1           1           0            0                0

select convert(numeric,'0,,0')
go
select convert(numeric,'0'+char(0)+'0')
go
select convert(numeric,'0'+char(0)+char(0)+'0')
go
select convert(numeric,'0'+char(0))
go