-99.1% is the change from 663 to 6
Calculation steps:
[( 6 - 663 ) ÷ 663] x 100 = -99.1%
Formula
Percentage change = [(6 - 663) / 663] x 100
Subtract the new number by the original number
6 - 663 = -657
-657 ÷ 663 = -0.9909502262443439
-0.9909502262443439 x 100 = -99.1%