-23.16% is the change from 639 to 491
Calculation steps:
[( 491 - 639 ) ÷ 639] x 100 = -23.16%
Formula
Percentage change = [(491 - 639) / 639] x 100
Subtract the new number by the original number
491 - 639 = -148
-148 ÷ 639 = -0.23161189358372458
-0.23161189358372458 x 100 = -23.16%