-62.53% is the change from 830 to 311
Calculation steps:
[( 311 - 830 ) ÷ 830] x 100 = -62.53%
Formula
Percentage change = [(311 - 830) / 830] x 100
Subtract the new number by the original number
311 - 830 = -519
-519 ÷ 830 = -0.6253012048192771
-0.6253012048192771 x 100 = -62.53%