-83.57% is the change from 639 to 105
Calculation steps:
[( 105 - 639 ) ÷ 639] x 100 = -83.57%
Formula
Percentage change = [(105 - 639) / 639] x 100
Subtract the new number by the original number
105 - 639 = -534
-534 ÷ 639 = -0.8356807511737089
-0.8356807511737089 x 100 = -83.57%