-0.2% is the change from 512 to 511
Calculation steps:
[( 511 - 512 ) ÷ 512] x 100 = -0.2%
Formula
Percentage change = [(511 - 512) / 512] x 100
Subtract the new number by the original number
511 - 512 = -1
-1 ÷ 512 = -0.001953125
-0.001953125 x 100 = -0.2%