1800% is the change from 15 to 285
Calculation steps:
[( 285 - 15 ) ÷ 15] x 100 = 1800%
Formula
Percentage change = [(285 - 15) / 15] x 100
Subtract the new number by the original number
285 - 15 = 270
270 ÷ 15 = 18
18 x 100 = 1800%
Example