-83.58% is the change from 609 to 100
Calculation steps:
[( 100 - 609 ) ÷ 609] x 100 = -83.58%
Formula
Percentage change = [(100 - 609) / 609] x 100
Subtract the new number by the original number
100 - 609 = -509
-509 ÷ 609 = -0.8357963875205254
-0.8357963875205254 x 100 = -83.58%