-66% is the change from 100 to 34
Calculation steps:
[( 34 - 100 ) ÷ 100] x 100 = -66%
Formula
Percentage change = [(34 - 100) / 100] x 100
Subtract the new number by the original number
34 - 100 = -66
-66 ÷ 100 = -0.66
-0.66 x 100 = -66%
Example