-99.07% is the change from 643 to 6
Calculation steps:
[( 6 - 643 ) ÷ 643] x 100 = -99.07%
Formula
Percentage change = [(6 - 643) / 643] x 100
Subtract the new number by the original number
6 - 643 = -637
-637 ÷ 643 = -0.9906687402799378
-0.9906687402799378 x 100 = -99.07%