am rezolvat pana la urma cu functia asta

create Function BigStringModulo(@BigNumString varchar(500), @Divisor int)
returns int
as
--Function BigStringModulo
--blindman, 1/18/2005
--Returns the Modulo value of a large number expressed as a string value.
--Does not verify that the string is a valid number!

begin
declare @WorkingString as varchar(500)
declare @CalcString as varchar(8)
set @WorkingString = @BigNumString

set @CalcString = left(@WorkingString, 8)
while @CalcString > @Divisor
begin
set @WorkingString = right(@WorkingString, len(@WorkingString) - len(@CalcString))
set @WorkingString = cast((@CalcString % @Divisor) as varchar) + @WorkingString
set @CalcString = left(@WorkingString, 8)
end

return cast(@CalcString as int)
end

multumesc.

alex.