the answer is "180"

179 + 1 = 180

The angle of a straight line = 180

The degrees that i cook my cakes at = 180

Out of 181, the randomness of this 问题 = 180

181 - 1 = 180

The number of 老友记 i'm hoping to have on 脸谱 由 the end of the 年 = 180

a 圈, 圈子 cut in half = 180 degrees

1 x 180 = 180

The amount of stupid things i do in my 日 = 180

the amount of ideas that people won't think of = 180

I DON'T KNOW!!??

what number do 你 get when 你 put a 0 on the end of the number 18