-90.08% is the change from 645 to 64
Calculation steps:
[( 64 - 645 ) ÷ 645] x 100 = -90.08%
Formula
Percentage change = [(64 - 645) / 645] x 100
Subtract the new number by the original number
64 - 645 = -581
-581 ÷ 645 = -0.9007751937984496
-0.9007751937984496 x 100 = -90.08%