-0.24% is the change from 421 to 420
Calculation steps:
[( 420 - 421 ) ÷ 421] x 100 = -0.24%
Formula
Percentage change = [(420 - 421) / 421] x 100
Subtract the new number by the original number
420 - 421 = -1
-1 ÷ 421 = -0.0023752969121140144
-0.0023752969121140144 x 100 = -0.24%