-99.64% is the change from 280 to 1
Calculation steps:
[( 1 - 280 ) ÷ 280] x 100 = -99.64%
Formula
Percentage change = [(1 - 280) / 280] x 100
Subtract the new number by the original number
1 - 280 = -279
-279 ÷ 280 = -0.9964285714285714
-0.9964285714285714 x 100 = -99.64%