640% is the change from 90 to 666
Calculation steps:
[( 666 - 90 ) ÷ 90] x 100 = 640%
Formula
Percentage change = [(666 - 90) / 90] x 100
Subtract the new number by the original number
666 - 90 = 576
576 ÷ 90 = 6.4
6.4 x 100 = 640%
Example