-62.65% is the change from 830 to 310
Calculation steps:
[( 310 - 830 ) ÷ 830] x 100 = -62.65%
Formula
Percentage change = [(310 - 830) / 830] x 100
Subtract the new number by the original number
310 - 830 = -520
-520 ÷ 830 = -0.6265060240963856
-0.6265060240963856 x 100 = -62.65%