Secondly, we know that the formula for the sum of the internal angles of a polygon is:

(n-2)* 180

Because each angle is 140 degrees, therefore:

140x= 180x-360

x=9

It's a nonagon.

That is ***8+7+6+5+4+3+2+ 1=36 (bar).

Third, the average difference of the series is:-1999-[-2003]=4.

500*4=2000

Then the nth item should be: -3, and the nth item should be: -3+4= 1.

[-3-(-2003)]/4+ 1=50 1

Therefore, the sum of the first 50 1 numbers in this column is the smallest.