-99.7% is the change from 668 to 2
Calculation steps:
[( 2 - 668 ) ÷ 668] x 100 = -99.7%
Formula
Percentage change = [(2 - 668) / 668] x 100
Subtract the new number by the original number
2 - 668 = -666
-666 ÷ 668 = -0.9970059880239521
-0.9970059880239521 x 100 = -99.7%