10% is the change from 400 to 440
Calculation steps:
[( 440 - 400 ) ÷ 400] x 100 = 10%
Formula
Percentage change = [(440 - 400) / 400] x 100
Subtract the new number by the original number
440 - 400 = 40
40 ÷ 400 = 0.1
0.1 x 100 = 10%
Example