-62.45% is the change from 815 to 306
Calculation steps:
[( 306 - 815 ) ÷ 815] x 100 = -62.45%
Formula
Percentage change = [(306 - 815) / 815] x 100
Subtract the new number by the original number
306 - 815 = -509
-509 ÷ 815 = -0.6245398773006134
-0.6245398773006134 x 100 = -62.45%