-90.3% is the change from 660 to 64
Calculation steps:
[( 64 - 660 ) ÷ 660] x 100 = -90.3%
Formula
Percentage change = [(64 - 660) / 660] x 100
Subtract the new number by the original number
64 - 660 = -596
-596 ÷ 660 = -0.9030303030303031
-0.9030303030303031 x 100 = -90.3%