-98.75% is the change from 80 to 1
Calculation steps:
[( 1 - 80 ) ÷ 80] x 100 = -98.75%
Formula
Percentage change = [(1 - 80) / 80] x 100
Subtract the new number by the original number
1 - 80 = -79
-79 ÷ 80 = -0.9875
-0.9875 x 100 = -98.75%
Example