-90.05% is the change from 643 to 64
Calculation steps:
[( 64 - 643 ) ÷ 643] x 100 = -90.05%
Formula
Percentage change = [(64 - 643) / 643] x 100
Subtract the new number by the original number
64 - 643 = -579
-579 ÷ 643 = -0.9004665629860031
-0.9004665629860031 x 100 = -90.05%