In your file in cell F3:
Code:
=MINIFS(Table1[OR No.],Table1[OR No.],">=" & FLOOR(Table1[@[OR No.]],50))
copied down gives the smallest number in a batch.
In cell G3:
Code:
=MAXIFS(Table1[OR No.],Table1[OR No.],"<=" & CEILING(Table1[@[OR No.]],50))
copied down gives the largest.