4200% is the change from 9 to 387
Calculation steps:
[( 387 - 9 ) ÷ 9] x 100 = 4200%
Formula
Percentage change = [(387 - 9) / 9] x 100
Subtract the new number by the original number
387 - 9 = 378
378 ÷ 9 = 42
42 x 100 = 4200%
Example