-90.88% is the change from 340 to 31
Calculation steps:
[( 31 - 340 ) ÷ 340] x 100 = -90.88%
Formula
Percentage change = [(31 - 340) / 340] x 100
Subtract the new number by the original number
31 - 340 = -309
-309 ÷ 340 = -0.9088235294117647
-0.9088235294117647 x 100 = -90.88%