-82.5% is the change from 320 to 56
Calculation steps:
[( 56 - 320 ) ÷ 320] x 100 = -82.5%
Formula
Percentage change = [(56 - 320) / 320] x 100
Subtract the new number by the original number
56 - 320 = -264
-264 ÷ 320 = -0.825
-0.825 x 100 = -82.5%
Example