-93.44% is the change from 320 to 21
Calculation steps:
[( 21 - 320 ) ÷ 320] x 100 = -93.44%
Formula
Percentage change = [(21 - 320) / 320] x 100
Subtract the new number by the original number
21 - 320 = -299
-299 ÷ 320 = -0.934375
-0.934375 x 100 = -93.44%
Example