-97.58% is the change from 620 to 15
Calculation steps:
[( 15 - 620 ) ÷ 620] x 100 = -97.58%
Formula
Percentage change = [(15 - 620) / 620] x 100
Subtract the new number by the original number
15 - 620 = -605
-605 ÷ 620 = -0.9758064516129032
-0.9758064516129032 x 100 = -97.58%