-93.78% is the change from 820 to 51
Calculation steps:
[( 51 - 820 ) ÷ 820] x 100 = -93.78%
Formula
Percentage change = [(51 - 820) / 820] x 100
Subtract the new number by the original number
51 - 820 = -769
-769 ÷ 820 = -0.9378048780487804
-0.9378048780487804 x 100 = -93.78%