-93.23% is the change from 310 to 21
Calculation steps:
[( 21 - 310 ) ÷ 310] x 100 = -93.23%
Formula
Percentage change = [(21 - 310) / 310] x 100
Subtract the new number by the original number
21 - 310 = -289
-289 ÷ 310 = -0.932258064516129
-0.932258064516129 x 100 = -93.23%