-49.3% is the change from 503 to 255
Calculation steps:
[( 255 - 503 ) ÷ 503] x 100 = -49.3%
Formula
Percentage change = [(255 - 503) / 503] x 100
Subtract the new number by the original number
255 - 503 = -248
-248 ÷ 503 = -0.49304174950298213
-0.49304174950298213 x 100 = -49.3%