-39.04% is the change from 830 to 506
Calculation steps:
[( 506 - 830 ) ÷ 830] x 100 = -39.04%
Formula
Percentage change = [(506 - 830) / 830] x 100
Subtract the new number by the original number
506 - 830 = -324
-324 ÷ 830 = -0.39036144578313253
-0.39036144578313253 x 100 = -39.04%