A square has zero obtuse angles.
To understand why, we first need to define what an obtuse angle is. An obtuse angle is any angle that measures more than 90 degrees but less than 180 degrees. In contrast, all angles in a square measure exactly 90 degrees, which makes them right angles.
Since there are no angles in a square that exceed 90 degrees, it follows that a square cannot have any obtuse angles at all. So, the answer is straightforward: a square has no obtuse angles.