-19.86% is the change from 836 to 670
Calculation steps:
[( 670 - 836 ) ÷ 836] x 100 = -19.86%
Formula
Percentage change = [(670 - 836) / 836] x 100
Subtract the new number by the original number
670 - 836 = -166
-166 ÷ 836 = -0.19856459330143542
-0.19856459330143542 x 100 = -19.86%