-90.34% is the change from 321 to 31
Calculation steps:
[( 31 - 321 ) ÷ 321] x 100 = -90.34%
Formula
Percentage change = [(31 - 321) / 321] x 100
Subtract the new number by the original number
31 - 321 = -290
-290 ÷ 321 = -0.9034267912772586
-0.9034267912772586 x 100 = -90.34%