1200% is the change from 30 to 390
Calculation steps:
[( 390 - 30 ) ÷ 30] x 100 = 1200%
Formula
Percentage change = [(390 - 30) / 30] x 100
Subtract the new number by the original number
390 - 30 = 360
360 ÷ 30 = 12
12 x 100 = 1200%
Example