-20.7% is the change from 512 to 406
Calculation steps:
[( 406 - 512 ) ÷ 512] x 100 = -20.7%
Formula
Percentage change = [(406 - 512) / 512] x 100
Subtract the new number by the original number
406 - 512 = -106
-106 ÷ 512 = -0.20703125
-0.20703125 x 100 = -20.7%