-94.09% is the change from 660 to 39
Calculation steps:
[( 39 - 660 ) ÷ 660] x 100 = -94.09%
Formula
Percentage change = [(39 - 660) / 660] x 100
Subtract the new number by the original number
39 - 660 = -621
-621 ÷ 660 = -0.9409090909090909
-0.9409090909090909 x 100 = -94.09%