-18.97% is the change from 643 to 521
Calculation steps:
[( 521 - 643 ) ÷ 643] x 100 = -18.97%
Formula
Percentage change = [(521 - 643) / 643] x 100
Subtract the new number by the original number
521 - 643 = -122
-122 ÷ 643 = -0.18973561430793157
-0.18973561430793157 x 100 = -18.97%