-97.64% is the change from 635 to 15
Calculation steps:
[( 15 - 635 ) ÷ 635] x 100 = -97.64%
Formula
Percentage change = [(15 - 635) / 635] x 100
Subtract the new number by the original number
15 - 635 = -620
-620 ÷ 635 = -0.9763779527559056
-0.9763779527559056 x 100 = -97.64%