-39.63% is the change from 820 to 495
Calculation steps:
[( 495 - 820 ) ÷ 820] x 100 = -39.63%
Formula
Percentage change = [(495 - 820) / 820] x 100
Subtract the new number by the original number
495 - 820 = -325
-325 ÷ 820 = -0.39634146341463417
-0.39634146341463417 x 100 = -39.63%