-3.11% is the change from 644 to 624
Calculation steps:
[( 624 - 644 ) ÷ 644] x 100 = -3.11%
Formula
Percentage change = [(624 - 644) / 644] x 100
Subtract the new number by the original number
624 - 644 = -20
-20 ÷ 644 = -0.031055900621118012
-0.031055900621118012 x 100 = -3.11%