-20.81% is the change from 644 to 510
Calculation steps:
[( 510 - 644 ) ÷ 644] x 100 = -20.81%
Formula
Percentage change = [(510 - 644) / 644] x 100
Subtract the new number by the original number
510 - 644 = -134
-134 ÷ 644 = -0.2080745341614907
-0.2080745341614907 x 100 = -20.81%