-33.88% is the change from 971 to 642
Calculation steps:
[( 642 - 971 ) ÷ 971] x 100 = -33.88%
Formula
Percentage change = [(642 - 971) / 971] x 100
Subtract the new number by the original number
642 - 971 = -329
-329 ÷ 971 = -0.3388259526261586
-0.3388259526261586 x 100 = -33.88%