-90.39% is the change from 666 to 64
Calculation steps:
[( 64 - 666 ) ÷ 666] x 100 = -90.39%
Formula
Percentage change = [(64 - 666) / 666] x 100
Subtract the new number by the original number
64 - 666 = -602
-602 ÷ 666 = -0.9039039039039038
-0.9039039039039038 x 100 = -90.39%