-99.85% is the change from 646 to 1
Calculation steps:
[( 1 - 646 ) ÷ 646] x 100 = -99.85%
Formula
Percentage change = [(1 - 646) / 646] x 100
Subtract the new number by the original number
1 - 646 = -645
-645 ÷ 646 = -0.9984520123839009
-0.9984520123839009 x 100 = -99.85%