-93.79% is the change from 821 to 51
Calculation steps:
[( 51 - 821 ) ÷ 821] x 100 = -93.79%
Formula
Percentage change = [(51 - 821) / 821] x 100
Subtract the new number by the original number
51 - 821 = -770
-770 ÷ 821 = -0.9378806333739342
-0.9378806333739342 x 100 = -93.79%