-50.18% is the change from 815 to 406
Calculation steps:
[( 406 - 815 ) ÷ 815] x 100 = -50.18%
Formula
Percentage change = [(406 - 815) / 815] x 100
Subtract the new number by the original number
406 - 815 = -409
-409 ÷ 815 = -0.501840490797546
-0.501840490797546 x 100 = -50.18%