2100% is the change from 18 to 396
Calculation steps:
[( 396 - 18 ) ÷ 18] x 100 = 2100%
Formula
Percentage change = [(396 - 18) / 18] x 100
Subtract the new number by the original number
396 - 18 = 378
378 ÷ 18 = 21
21 x 100 = 2100%
Example