-99.07% is the change from 645 to 6
Calculation steps:
[( 6 - 645 ) ÷ 645] x 100 = -99.07%
Formula
Percentage change = [(6 - 645) / 645] x 100
Subtract the new number by the original number
6 - 645 = -639
-639 ÷ 645 = -0.9906976744186047
-0.9906976744186047 x 100 = -99.07%