Without seeing your query this will have to be very generic, but something like the following should work:
SELECT TO_CHAR(col1) || '-' || TO_CHAR(col1+1) as "column 1",
col2 as "column 2"
FROM (SELECT col1,
SUM(col2) as col2
FROM sometable
WHERE something = something_else
GROUP BY col1)
The above is Oracle syntax (the TO_CHAR and || string concatenations) but should give you a good idea of how to proceed.
EDIT: In SQL Server try the following:
SELECT CAST(col1 AS NVARCHAR(100)) + N'-' +
CAST(col1+1 AS NVARCHAR(100)) AS "column 1",
col2 as "column 2"
FROM (SELECT col1,
SUM(col2) as col2
FROM sometable
WHERE something = something_else
GROUP BY col1)
Share and enjoy.