-36.46% is the change from 820 to 521
Calculation steps:
[( 521 - 820 ) ÷ 820] x 100 = -36.46%
Formula
Percentage change = [(521 - 820) / 820] x 100
Subtract the new number by the original number
521 - 820 = -299
-299 ÷ 820 = -0.3646341463414634
-0.3646341463414634 x 100 = -36.46%