70.26% is the change from 390 to 664
Calculation steps:
[( 664 - 390 ) ÷ 390] x 100 = 70.26%
Formula
Percentage change = [(664 - 390) / 390] x 100
Subtract the new number by the original number
664 - 390 = 274
274 ÷ 390 = 0.7025641025641025
0.7025641025641025 x 100 = 70.26%