The internal angle sum of a quadrilateral is :
C. 360°
The sum of internal angles of a polygon is determined by a formula :

where n represents number of sides.
In a quadrilateral there are four sides,
So, plugging 4 in the formula :
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Thanks merry Christmas to you
5 is in the ten thousands place now. Since the next digit (a 6) is greater than 5, we must round UP: 360000 is to the nearest ten thousand.