-2% is the change from 400 to 392
Calculation steps:
[( 392 - 400 ) ÷ 400] x 100 = -2%
Formula
Percentage change = [(392 - 400) / 400] x 100
Subtract the new number by the original number
392 - 400 = -8
-8 ÷ 400 = -0.02
-0.02 x 100 = -2%
Example