-50.53% is the change from 851 to 421
Calculation steps:
[( 421 - 851 ) ÷ 851] x 100 = -50.53%
Formula
Percentage change = [(421 - 851) / 851] x 100
Subtract the new number by the original number
421 - 851 = -430
-430 ÷ 851 = -0.5052878965922444
-0.5052878965922444 x 100 = -50.53%