-40.18% is the change from 871 to 521
Calculation steps:
[( 521 - 871 ) ÷ 871] x 100 = -40.18%
Formula
Percentage change = [(521 - 871) / 871] x 100
Subtract the new number by the original number
521 - 871 = -350
-350 ÷ 871 = -0.4018369690011481
-0.4018369690011481 x 100 = -40.18%