-48.72% is the change from 821 to 421
Calculation steps:
[( 421 - 821 ) ÷ 821] x 100 = -48.72%
Formula
Percentage change = [(421 - 821) / 821] x 100
Subtract the new number by the original number
421 - 821 = -400
-400 ÷ 821 = -0.48721071863581
-0.48721071863581 x 100 = -48.72%