-21.03% is the change from 642 to 507
Calculation steps:
[( 507 - 642 ) ÷ 642] x 100 = -21.03%
Formula
Percentage change = [(507 - 642) / 642] x 100
Subtract the new number by the original number
507 - 642 = -135
-135 ÷ 642 = -0.2102803738317757
-0.2102803738317757 x 100 = -21.03%