-97.66% is the change from 641 to 15
Calculation steps:
[( 15 - 641 ) ÷ 641] x 100 = -97.66%
Formula
Percentage change = [(15 - 641) / 641] x 100
Subtract the new number by the original number
15 - 641 = -626
-626 ÷ 641 = -0.9765990639625585
-0.9765990639625585 x 100 = -97.66%