-80.59% is the change from 340 to 66
Calculation steps:
[( 66 - 340 ) ÷ 340] x 100 = -80.59%
Formula
Percentage change = [(66 - 340) / 340] x 100
Subtract the new number by the original number
66 - 340 = -274
-274 ÷ 340 = -0.8058823529411765
-0.8058823529411765 x 100 = -80.59%