-86.07% is the change from 646 to 90
Calculation steps:
[( 90 - 646 ) ÷ 646] x 100 = -86.07%
Formula
Percentage change = [(90 - 646) / 646] x 100
Subtract the new number by the original number
90 - 646 = -556
-556 ÷ 646 = -0.8606811145510835
-0.8606811145510835 x 100 = -86.07%