-21.52% is the change from 646 to 507
Calculation steps:
[( 507 - 646 ) ÷ 646] x 100 = -21.52%
Formula
Percentage change = [(507 - 646) / 646] x 100
Subtract the new number by the original number
507 - 646 = -139
-139 ÷ 646 = -0.21517027863777088
-0.21517027863777088 x 100 = -21.52%