-39.39% is the change from 820 to 497
Calculation steps:
[( 497 - 820 ) ÷ 820] x 100 = -39.39%
Formula
Percentage change = [(497 - 820) / 820] x 100
Subtract the new number by the original number
497 - 820 = -323
-323 ÷ 820 = -0.39390243902439026
-0.39390243902439026 x 100 = -39.39%