-97.68% is the change from 647 to 15
Calculation steps:
[( 15 - 647 ) ÷ 647] x 100 = -97.68%
Formula
Percentage change = [(15 - 647) / 647] x 100
Subtract the new number by the original number
15 - 647 = -632
-632 ÷ 647 = -0.9768160741885626
-0.9768160741885626 x 100 = -97.68%