-66.5% is the change from 815 to 273
Calculation steps:
[( 273 - 815 ) ÷ 815] x 100 = -66.5%
Formula
Percentage change = [(273 - 815) / 815] x 100
Subtract the new number by the original number
273 - 815 = -542
-542 ÷ 815 = -0.6650306748466258
-0.6650306748466258 x 100 = -66.5%