-1.85% is the change from 650 to 638
Calculation steps:
[( 638 - 650 ) ÷ 650] x 100 = -1.85%
Formula
Percentage change = [(638 - 650) / 650] x 100
Subtract the new number by the original number
638 - 650 = -12
-12 ÷ 650 = -0.018461538461538463
-0.018461538461538463 x 100 = -1.85%