Question 143400
You haven't indicated whether or not this is a REGULAR polygon (one whose sides are all of equal length) but I'll assume that it is.
You can start with the formula for the sum of the interior angles (S) of a regular polygon of n-sides:
{{{S = (n-2)180}}} Since you know that this sum is 1440 degrees, you can substitute this into the formula and solve for n, the number of sides.
{{{1440 = (n-2)180}}} Divide both sides by 180
{{{8 = n-2}}} Add 2 to both sides.
{{{n = 10}}}
The regular polygon has 10 sides.  This is known as a decagon.