-97.55% is the change from 857 to 21
Calculation steps:
[( 21 - 857 ) ÷ 857] x 100 = -97.55%
Formula
Percentage change = [(21 - 857) / 857] x 100
Subtract the new number by the original number
21 - 857 = -836
-836 ÷ 857 = -0.9754959159859977
-0.9754959159859977 x 100 = -97.55%