-61.59% is the change from 820 to 315
Calculation steps:
[( 315 - 820 ) ÷ 820] x 100 = -61.59%
Formula
Percentage change = [(315 - 820) / 820] x 100
Subtract the new number by the original number
315 - 820 = -505
-505 ÷ 820 = -0.6158536585365854
-0.6158536585365854 x 100 = -61.59%