-0.15% is the change from 646 to 645
Calculation steps:
[( 645 - 646 ) ÷ 646] x 100 = -0.15%
Formula
Percentage change = [(645 - 646) / 646] x 100
Subtract the new number by the original number
645 - 646 = -1
-1 ÷ 646 = -0.0015479876160990713
-0.0015479876160990713 x 100 = -0.15%