-80.78% is the change from 666 to 128
Calculation steps:
[( 128 - 666 ) ÷ 666] x 100 = -80.78%
Formula
Percentage change = [(128 - 666) / 666] x 100
Subtract the new number by the original number
128 - 666 = -538
-538 ÷ 666 = -0.8078078078078078
-0.8078078078078078 x 100 = -80.78%