If your table columns contains duplicate data and If you directly apply row_ number() and create PARTITION on column, there is chance to have result in duplicated row and with row number value.
To remove duplicate row, you need one more INNER query in from clause which eliminates duplicate rows and then it will give output to it's foremost outer FROM clause where you can apply PARTITION and ROW_NUMBER ().
As like below example:
SELECT DATE, STATUS, TITLE, ROW_NUMBER() OVER (PARTITION BY DATE, STATUS, TITLE ORDER BY QUANTITY ASC) AS Row_Num
FROM (
SELECT DISTINCT <column names>...
) AS tbl