-86.38% is the change from 639 to 87
Calculation steps:
[( 87 - 639 ) ÷ 639] x 100 = -86.38%
Formula
Percentage change = [(87 - 639) / 639] x 100
Subtract the new number by the original number
87 - 639 = -552
-552 ÷ 639 = -0.863849765258216
-0.863849765258216 x 100 = -86.38%