-39.15% is the change from 820 to 499
Calculation steps:
[( 499 - 820 ) ÷ 820] x 100 = -39.15%
Formula
Percentage change = [(499 - 820) / 820] x 100
Subtract the new number by the original number
499 - 820 = -321
-321 ÷ 820 = -0.39146341463414636
-0.39146341463414636 x 100 = -39.15%