-22.83% is the change from 828 to 639
Calculation steps:
[( 639 - 828 ) ÷ 828] x 100 = -22.83%
Formula
Percentage change = [(639 - 828) / 828] x 100
Subtract the new number by the original number
639 - 828 = -189
-189 ÷ 828 = -0.22826086956521738
-0.22826086956521738 x 100 = -22.83%