-50.15% is the change from 664 to 331
Calculation steps:
[( 331 - 664 ) ÷ 664] x 100 = -50.15%
Formula
Percentage change = [(331 - 664) / 664] x 100
Subtract the new number by the original number
331 - 664 = -333
-333 ÷ 664 = -0.5015060240963856
-0.5015060240963856 x 100 = -50.15%