-49.71% is the change from 511 to 257
Calculation steps:
[( 257 - 511 ) ÷ 511] x 100 = -49.71%
Formula
Percentage change = [(257 - 511) / 511] x 100
Subtract the new number by the original number
257 - 511 = -254
-254 ÷ 511 = -0.49706457925636005
-0.49706457925636005 x 100 = -49.71%