-0.63% is the change from 639 to 635
Calculation steps:
[( 635 - 639 ) ÷ 639] x 100 = -0.63%
Formula
Percentage change = [(635 - 639) / 639] x 100
Subtract the new number by the original number
635 - 639 = -4
-4 ÷ 639 = -0.006259780907668232
-0.006259780907668232 x 100 = -0.63%