-89.98% is the change from 509 to 51
Calculation steps:
[( 51 - 509 ) ÷ 509] x 100 = -89.98%
Formula
Percentage change = [(51 - 509) / 509] x 100
Subtract the new number by the original number
51 - 509 = -458
-458 ÷ 509 = -0.899803536345776
-0.899803536345776 x 100 = -89.98%