-34.36% is the change from 978 to 642
Calculation steps:
[( 642 - 978 ) ÷ 978] x 100 = -34.36%
Formula
Percentage change = [(642 - 978) / 978] x 100
Subtract the new number by the original number
642 - 978 = -336
-336 ÷ 978 = -0.34355828220858897
-0.34355828220858897 x 100 = -34.36%