-1.73% is the change from 521 to 512
Calculation steps:
[( 512 - 521 ) ÷ 521] x 100 = -1.73%
Formula
Percentage change = [(512 - 521) / 521] x 100
Subtract the new number by the original number
512 - 521 = -9
-9 ÷ 521 = -0.01727447216890595
-0.01727447216890595 x 100 = -1.73%