-51.59% is the change from 661 to 320
Calculation steps:
[( 320 - 661 ) ÷ 661] x 100 = -51.59%
Formula
Percentage change = [(320 - 661) / 661] x 100
Subtract the new number by the original number
320 - 661 = -341
-341 ÷ 661 = -0.5158850226928896
-0.5158850226928896 x 100 = -51.59%