-83.4% is the change from 512 to 85
Calculation steps:
[( 85 - 512 ) ÷ 512] x 100 = -83.4%
Formula
Percentage change = [(85 - 512) / 512] x 100
Subtract the new number by the original number
85 - 512 = -427
-427 ÷ 512 = -0.833984375
-0.833984375 x 100 = -83.4%