-66.51% is the change from 830 to 278
Calculation steps:
[( 278 - 830 ) ÷ 830] x 100 = -66.51%
Formula
Percentage change = [(278 - 830) / 830] x 100
Subtract the new number by the original number
278 - 830 = -552
-552 ÷ 830 = -0.6650602409638554
-0.6650602409638554 x 100 = -66.51%