2600% is the change from 15 to 405
Calculation steps:
[( 405 - 15 ) ÷ 15] x 100 = 2600%
Formula
Percentage change = [(405 - 15) / 15] x 100
Subtract the new number by the original number
405 - 15 = 390
390 ÷ 15 = 26
26 x 100 = 2600%
Example