1230% is the change from 30 to 399
Calculation steps:
[( 399 - 30 ) ÷ 30] x 100 = 1230%
Formula
Percentage change = [(399 - 30) / 30] x 100
Subtract the new number by the original number
399 - 30 = 369
369 ÷ 30 = 12.3
12.3 x 100 = 1230%
Example