-89.8% is the change from 500 to 51
Calculation steps:
[( 51 - 500 ) ÷ 500] x 100 = -89.8%
Formula
Percentage change = [(51 - 500) / 500] x 100
Subtract the new number by the original number
51 - 500 = -449
-449 ÷ 500 = -0.898
-0.898 x 100 = -89.8%
Example