Convert NVARCHAR to INT skipping non convertibles

GROUP BY age / 10

CREATE TABLE #temp (age NVARCHAR(20))

INSERT INTO #temp
    SELECT '22'
    UNION
SELECT '24'
    UNION
SELECT '20.10.1984'
    UNION
SELECT '50'

SELECT age/10, COUNT(*)
    FROM #temp
    WHERE ISNUMERIC(age) = 1
    GROUP BY age/10

DROP TABLE #temp