-2.5% is the change from 839 to 818
Calculation steps:
[( 818 - 839 ) ÷ 839] x 100 = -2.5%
Formula
Percentage change = [(818 - 839) / 839] x 100
Subtract the new number by the original number
818 - 839 = -21
-21 ÷ 839 = -0.025029797377830752
-0.025029797377830752 x 100 = -2.5%