-50.92% is the change from 813 to 399
Calculation steps:
[( 399 - 813 ) ÷ 813] x 100 = -50.92%
Formula
Percentage change = [(399 - 813) / 813] x 100
Subtract the new number by the original number
399 - 813 = -414
-414 ÷ 813 = -0.5092250922509225
-0.5092250922509225 x 100 = -50.92%