-98.7% is the change from 999 to 13
Calculation steps:
[( 13 - 999 ) ÷ 999] x 100 = -98.7%
Formula
Percentage change = [(13 - 999) / 999] x 100
Subtract the new number by the original number
13 - 999 = -986
-986 ÷ 999 = -0.986986986986987
-0.986986986986987 x 100 = -98.7%