-85.1% is the change from 671 to 100
Calculation steps:
[( 100 - 671 ) ÷ 671] x 100 = -85.1%
Formula
Percentage change = [(100 - 671) / 671] x 100
Subtract the new number by the original number
100 - 671 = -571
-571 ÷ 671 = -0.8509687034277198
-0.8509687034277198 x 100 = -85.1%