-33.95% is the change from 966 to 638
Calculation steps:
[( 638 - 966 ) ÷ 966] x 100 = -33.95%
Formula
Percentage change = [(638 - 966) / 966] x 100
Subtract the new number by the original number
638 - 966 = -328
-328 ÷ 966 = -0.33954451345755693
-0.33954451345755693 x 100 = -33.95%