-51.08% is the change from 511 to 250
Calculation steps:
[( 250 - 511 ) ÷ 511] x 100 = -51.08%
Formula
Percentage change = [(250 - 511) / 511] x 100
Subtract the new number by the original number
250 - 511 = -261
-261 ÷ 511 = -0.5107632093933464
-0.5107632093933464 x 100 = -51.08%