set @result = cast (@@rowcount as varchar);

declare @result varchar (5);
create table #n (n int);

insert into #n
select 
	top 3 row_number() over (order by [object_id])
	from sys.objects;

-- @@rowcount is equal to 3 after the insert, and @@rowcount is equal 
--to 1 after the set below is executed, so set @result = ... does indeed 
--sets the rowcount. The confusion comes from the fact that the statements 
-- such as set ansi_nulls, quoted_identifier or whatever other set do not
-- have so-called rows affected so those set statements reset the @@rowcount 
-- to 0, that is all. They still change the value of the @@rowcount though :)
set @result = cast (@@rowcount as varchar);

select @result = @result + cast (@@rowcount as varchar) from #n; 
select @result + cast (@@rowcount as varchar);