-50.24% is the change from 850 to 423
Calculation steps:
[( 423 - 850 ) ÷ 850] x 100 = -50.24%
Formula
Percentage change = [(423 - 850) / 850] x 100
Subtract the new number by the original number
423 - 850 = -427
-427 ÷ 850 = -0.5023529411764706
-0.5023529411764706 x 100 = -50.24%