-96.46% is the change from 509 to 18
Calculation steps:
[( 18 - 509 ) ÷ 509] x 100 = -96.46%
Formula
Percentage change = [(18 - 509) / 509] x 100
Subtract the new number by the original number
18 - 509 = -491
-491 ÷ 509 = -0.9646365422396856
-0.9646365422396856 x 100 = -96.46%