-34.59% is the change from 639 to 418
Calculation steps:
[( 418 - 639 ) ÷ 639] x 100 = -34.59%
Formula
Percentage change = [(418 - 639) / 639] x 100
Subtract the new number by the original number
418 - 639 = -221
-221 ÷ 639 = -0.3458528951486698
-0.3458528951486698 x 100 = -34.59%