-20.57% is the change from 637 to 506
Calculation steps:
[( 506 - 637 ) ÷ 637] x 100 = -20.57%
Formula
Percentage change = [(506 - 637) / 637] x 100
Subtract the new number by the original number
506 - 637 = -131
-131 ÷ 637 = -0.20565149136577707
-0.20565149136577707 x 100 = -20.57%