*The word pentagon is a name given to a polygon that has 5 sides. So in this case, the question should have used the word polygon instead of pentagon.
Sum of interior angles = (n - 2) x 180 where n is the number of sides.
The sum of the interior angles = 900
(n - 2) x 180 = 900
n - 2 = 900 ÷ 180
n - 2 = 5
n = 5 + 2
n = 7
Answer: This is a 7-sided polygon.
