-34.01% is the change from 638 to 421
Calculation steps:
[( 421 - 638 ) ÷ 638] x 100 = -34.01%
Formula
Percentage change = [(421 - 638) / 638] x 100
Subtract the new number by the original number
421 - 638 = -217
-217 ÷ 638 = -0.3401253918495298
-0.3401253918495298 x 100 = -34.01%