-99.6% is the change from 250 to 1
Calculation steps:
[( 1 - 250 ) ÷ 250] x 100 = -99.6%
Formula
Percentage change = [(1 - 250) / 250] x 100
Subtract the new number by the original number
1 - 250 = -249
-249 ÷ 250 = -0.996
-0.996 x 100 = -99.6%
Example