-97.03% is the change from 639 to 19
Calculation steps:
[( 19 - 639 ) ÷ 639] x 100 = -97.03%
Formula
Percentage change = [(19 - 639) / 639] x 100
Subtract the new number by the original number
19 - 639 = -620
-620 ÷ 639 = -0.9702660406885759
-0.9702660406885759 x 100 = -97.03%