-3.91% is the change from 511 to 491
Calculation steps:
[( 491 - 511 ) ÷ 511] x 100 = -3.91%
Formula
Percentage change = [(491 - 511) / 511] x 100
Subtract the new number by the original number
491 - 511 = -20
-20 ÷ 511 = -0.03913894324853229
-0.03913894324853229 x 100 = -3.91%