-51.1% is the change from 820 to 401
Calculation steps:
[( 401 - 820 ) ÷ 820] x 100 = -51.1%
Formula
Percentage change = [(401 - 820) / 820] x 100
Subtract the new number by the original number
401 - 820 = -419
-419 ÷ 820 = -0.5109756097560976
-0.5109756097560976 x 100 = -51.1%