67.5% is the change from 400 to 670
Calculation steps:
[( 670 - 400 ) ÷ 400] x 100 = 67.5%
Formula
Percentage change = [(670 - 400) / 400] x 100
Subtract the new number by the original number
670 - 400 = 270
270 ÷ 400 = 0.675
0.675 x 100 = 67.5%
Example