-20.87% is the change from 642 to 508
Calculation steps:
[( 508 - 642 ) ÷ 642] x 100 = -20.87%
Formula
Percentage change = [(508 - 642) / 642] x 100
Subtract the new number by the original number
508 - 642 = -134
-134 ÷ 642 = -0.2087227414330218
-0.2087227414330218 x 100 = -20.87%