-89.74% is the change from 643 to 66
Calculation steps:
[( 66 - 643 ) ÷ 643] x 100 = -89.74%
Formula
Percentage change = [(66 - 643) / 643] x 100
Subtract the new number by the original number
66 - 643 = -577
-577 ÷ 643 = -0.8973561430793157
-0.8973561430793157 x 100 = -89.74%