select last value from each Records and bind to Gridview

Alternativelly, you can use REPLACE[^] function.

DECLARE @tmp TABLE (StringNumbers VARCHAR(10))

INSERT INTO @tmp (StringNumbers)
VALUES('100'), ('100/1'),
('100/2'), ('101'),
('101/1'), ('102'),
('102/1'), ('102/2'),
('103'), ('104')


SELECT StringNumbers, CONVERT(FLOAT, REPLACE(StringNumbers ,'/','.')) AS MyNumber
FROM @tmp
ORDER BY CONVERT(FLOAT, REPLACE(StringNumbers ,'/','.'))

Think of it and change the code to your needs ;)

The problem with that is that "100/1" is a string based value, so it will work with a string based comparison, rather than numeric. You can do it, but it's pretty cumbersome in SQL - I'd do it in a "proper" programing language where it's pretty simple.

SELECT MAX(ID) FROM MyTable
GROUP BY SUBSTRING(ID, 0, CASE WHEN CHARINDEX('/', ID) > 0
                               THEN CHARINDEX('/', ID)
                               ELSE LEN(ID)
                          END)

If you can change your DB so it's two fields, it becomes a lot easier!