-73.24% is the change from 639 to 171
Calculation steps:
[( 171 - 639 ) ÷ 639] x 100 = -73.24%
Formula
Percentage change = [(171 - 639) / 639] x 100
Subtract the new number by the original number
171 - 639 = -468
-468 ÷ 639 = -0.7323943661971831
-0.7323943661971831 x 100 = -73.24%