-50.12% is the change from 820 to 409
Calculation steps:
[( 409 - 820 ) ÷ 820] x 100 = -50.12%
Formula
Percentage change = [(409 - 820) / 820] x 100
Subtract the new number by the original number
409 - 820 = -411
-411 ÷ 820 = -0.501219512195122
-0.501219512195122 x 100 = -50.12%