-49.6% is the change from 506 to 255
Calculation steps:
[( 255 - 506 ) ÷ 506] x 100 = -49.6%
Formula
Percentage change = [(255 - 506) / 506] x 100
Subtract the new number by the original number
255 - 506 = -251
-251 ÷ 506 = -0.49604743083003955
-0.49604743083003955 x 100 = -49.6%