-73.6% is the change from 250 to 66
Calculation steps:
[( 66 - 250 ) ÷ 250] x 100 = -73.6%
Formula
Percentage change = [(66 - 250) / 250] x 100
Subtract the new number by the original number
66 - 250 = -184
-184 ÷ 250 = -0.736
-0.736 x 100 = -73.6%
Example