-99.05% is the change from 421 to 4
Calculation steps:
[( 4 - 421 ) ÷ 421] x 100 = -99.05%
Formula
Percentage change = [(4 - 421) / 421] x 100
Subtract the new number by the original number
4 - 421 = -417
-417 ÷ 421 = -0.9904988123515439
-0.9904988123515439 x 100 = -99.05%