-97.67% is the change from 643 to 15
Calculation steps:
[( 15 - 643 ) ÷ 643] x 100 = -97.67%
Formula
Percentage change = [(15 - 643) / 643] x 100
Subtract the new number by the original number
15 - 643 = -628
-628 ÷ 643 = -0.9766718506998445
-0.9766718506998445 x 100 = -97.67%