-50.4% is the change from 506 to 251
Calculation steps:
[( 251 - 506 ) ÷ 506] x 100 = -50.4%
Formula
Percentage change = [(251 - 506) / 506] x 100
Subtract the new number by the original number
251 - 506 = -255
-255 ÷ 506 = -0.5039525691699605
-0.5039525691699605 x 100 = -50.4%