-93.74% is the change from 815 to 51
Calculation steps:
[( 51 - 815 ) ÷ 815] x 100 = -93.74%
Formula
Percentage change = [(51 - 815) / 815] x 100
Subtract the new number by the original number
51 - 815 = -764
-764 ÷ 815 = -0.9374233128834356
-0.9374233128834356 x 100 = -93.74%