-99.76% is the change from 421 to 1
Calculation steps:
[( 1 - 421 ) ÷ 421] x 100 = -99.76%
Formula
Percentage change = [(1 - 421) / 421] x 100
Subtract the new number by the original number
1 - 421 = -420
-420 ÷ 421 = -0.997624703087886
-0.997624703087886 x 100 = -99.76%