Interesting thread.

Combining my favorite parts from all replies I think I would now do something like this:

DECLARE @Number Decimal(10,2)

SET @Number = 12345678.90

DECLARE @Number_String VarChar(25)

SET @Number_String = Convert(VarChar(25), @Number)

;WITH

T1 AS (SELECT 1 X UNION ALL SELECT 1 X),

Sequence AS (SELECT Row_Number() OVER (ORDER BY A.X) AS Number FROM T1 A, T1 B, T1 C, T1 D)

SELECT

(

SELECT

SUBSTRING(@Number_String, Sequence.Number, 1)

FROM

Sequence

WHERE

Sequence.Number <= LEN(@Number_String)

ORDER BY

Sequence.Number DESC

FOR XML PATH(''), TYPE

)

.value('.', 'VARCHAR(25)');