-9.99% is the change from 711 to 640
Calculation steps:
[( 640 - 711 ) ÷ 711] x 100 = -9.99%
Formula
Percentage change = [(640 - 711) / 711] x 100
Subtract the new number by the original number
640 - 711 = -71
-71 ÷ 711 = -0.09985935302390998
-0.09985935302390998 x 100 = -9.99%