-0.47% is the change from 639 to 636
Calculation steps:
[( 636 - 639 ) ÷ 639] x 100 = -0.47%
Formula
Percentage change = [(636 - 639) / 639] x 100
Subtract the new number by the original number
636 - 639 = -3
-3 ÷ 639 = -0.004694835680751174
-0.004694835680751174 x 100 = -0.47%