869.7% is the change from 66 to 640
Calculation steps:
[( 640 - 66 ) ÷ 66] x 100 = 869.7%
Formula
Percentage change = [(640 - 66) / 66] x 100
Subtract the new number by the original number
640 - 66 = 574
574 ÷ 66 = 8.696969696969697
8.696969696969697 x 100 = 869.7%