-90.9% is the change from 670 to 61
Calculation steps:
[( 61 - 670 ) ÷ 670] x 100 = -90.9%
Formula
Percentage change = [(61 - 670) / 670] x 100
Subtract the new number by the original number
61 - 670 = -609
-609 ÷ 670 = -0.908955223880597
-0.908955223880597 x 100 = -90.9%