-97.34% is the change from 639 to 17
Calculation steps:
[( 17 - 639 ) ÷ 639] x 100 = -97.34%
Formula
Percentage change = [(17 - 639) / 639] x 100
Subtract the new number by the original number
17 - 639 = -622
-622 ÷ 639 = -0.97339593114241
-0.97339593114241 x 100 = -97.34%