-90.23% is the change from 215 to 21
Calculation steps:
[( 21 - 215 ) ÷ 215] x 100 = -90.23%
Formula
Percentage change = [(21 - 215) / 215] x 100
Subtract the new number by the original number
21 - 215 = -194
-194 ÷ 215 = -0.9023255813953488
-0.9023255813953488 x 100 = -90.23%