-50.1% is the change from 503 to 251
Calculation steps:
[( 251 - 503 ) ÷ 503] x 100 = -50.1%
Formula
Percentage change = [(251 - 503) / 503] x 100
Subtract the new number by the original number
251 - 503 = -252
-252 ÷ 503 = -0.5009940357852882
-0.5009940357852882 x 100 = -50.1%