Listing 1: Script That Stores Integer as Decimal and Character Value and Shows the 
Results
DECLARE @MyLargeNumber DECIMAL (20, 0)
SET @MyLargeNumber = 99999999999999999999
SELECT @MyLargeNumber
SELECT DATALENGTH(@MyLargeNumber)

           
------------------------
--99999999999999999999

--(1 row(s) affected)

-------------
--13

--(1 row(s) affected)

DECLARE @MyLargeNumberChar char(20)
SET @MyLargeNumberChar = '99999999999999999999'
SELECT @MyLargeNumberChar
SELECT DATALENGTH(@MyLargeNumberChar)

----------------------
--99999999999999999999

--(1 row(s) affected)

     
---------------
--20

--(1 row(s) affected)