-91.83% is the change from 257 to 21
Calculation steps:
[( 21 - 257 ) ÷ 257] x 100 = -91.83%
Formula
Percentage change = [(21 - 257) / 257] x 100
Subtract the new number by the original number
21 - 257 = -236
-236 ÷ 257 = -0.9182879377431906
-0.9182879377431906 x 100 = -91.83%