-70% is the change from 270 to 81
Calculation steps:
[( 81 - 270 ) ÷ 270] x 100 = -70%
Formula
Percentage change = [(81 - 270) / 270] x 100
Subtract the new number by the original number
81 - 270 = -189
-189 ÷ 270 = -0.7
-0.7 x 100 = -70%
Example