70% is the change from 400 to 680
Calculation steps:
[( 680 - 400 ) ÷ 400] x 100 = 70%
Formula
Percentage change = [(680 - 400) / 400] x 100
Subtract the new number by the original number
680 - 400 = 280
280 ÷ 400 = 0.7
0.7 x 100 = 70%
Example