-68.94% is the change from 821 to 255
Calculation steps:
[( 255 - 821 ) ÷ 821] x 100 = -68.94%
Formula
Percentage change = [(255 - 821) / 821] x 100
Subtract the new number by the original number
255 - 821 = -566
-566 ÷ 821 = -0.6894031668696712
-0.6894031668696712 x 100 = -68.94%