-33.59% is the change from 512 to 340
Calculation steps:
[( 340 - 512 ) ÷ 512] x 100 = -33.59%
Formula
Percentage change = [(340 - 512) / 512] x 100
Subtract the new number by the original number
340 - 512 = -172
-172 ÷ 512 = -0.3359375
-0.3359375 x 100 = -33.59%