-89.77% is the change from 645 to 66
Calculation steps:
[( 66 - 645 ) ÷ 645] x 100 = -89.77%
Formula
Percentage change = [(66 - 645) / 645] x 100
Subtract the new number by the original number
66 - 645 = -579
-579 ÷ 645 = -0.8976744186046511
-0.8976744186046511 x 100 = -89.77%