10400% is the change from 8 to 840
Calculation steps:
[( 840 - 8 ) ÷ 8] x 100 = 10400%
Formula
Percentage change = [(840 - 8) / 8] x 100
Subtract the new number by the original number
840 - 8 = 832
832 ÷ 8 = 104
104 x 100 = 10400%
Example