-90.1% is the change from 515 to 51
Calculation steps:
[( 51 - 515 ) ÷ 515] x 100 = -90.1%
Formula
Percentage change = [(51 - 515) / 515] x 100
Subtract the new number by the original number
51 - 515 = -464
-464 ÷ 515 = -0.9009708737864077
-0.9009708737864077 x 100 = -90.1%