100% is the change from 408 to 816
Calculation steps:
[( 816 - 408 ) ÷ 408] x 100 = 100%
Formula
Percentage change = [(816 - 408) / 408] x 100
Subtract the new number by the original number
816 - 408 = 408
408 ÷ 408 = 1
1 x 100 = 100%
Example