-40.12% is the change from 511 to 306
Calculation steps:
[( 306 - 511 ) ÷ 511] x 100 = -40.12%
Formula
Percentage change = [(306 - 511) / 511] x 100
Subtract the new number by the original number
306 - 511 = -205
-205 ÷ 511 = -0.40117416829745595
-0.40117416829745595 x 100 = -40.12%