-99.88% is the change from 820 to 1
Calculation steps:
[( 1 - 820 ) ÷ 820] x 100 = -99.88%
Formula
Percentage change = [(1 - 820) / 820] x 100
Subtract the new number by the original number
1 - 820 = -819
-819 ÷ 820 = -0.998780487804878
-0.998780487804878 x 100 = -99.88%