8400% is the change from 1 to 85
Calculation steps:
[( 85 - 1 ) ÷ 1] x 100 = 8400%
Formula
Percentage change = [(85 - 1) / 1] x 100
Subtract the new number by the original number
85 - 1 = 84
84 ÷ 1 = 84
84 x 100 = 8400%
Example