-89.4% is the change from 670 to 71
Calculation steps:
[( 71 - 670 ) ÷ 670] x 100 = -89.4%
Formula
Percentage change = [(71 - 670) / 670] x 100
Subtract the new number by the original number
71 - 670 = -599
-599 ÷ 670 = -0.8940298507462686
-0.8940298507462686 x 100 = -89.4%