-18.85% is the change from 642 to 521
Calculation steps:
[( 521 - 642 ) ÷ 642] x 100 = -18.85%
Formula
Percentage change = [(521 - 642) / 642] x 100
Subtract the new number by the original number
521 - 642 = -121
-121 ÷ 642 = -0.18847352024922118
-0.18847352024922118 x 100 = -18.85%