100% is the change from 180 to 360
Calculation steps:
[( 360 - 180 ) ÷ 180] x 100 = 100%
Formula
Percentage change = [(360 - 180) / 180] x 100
Subtract the new number by the original number
360 - 180 = 180
180 ÷ 180 = 1
1 x 100 = 100%
Example