-97.06% is the change from 511 to 15
Calculation steps:
[( 15 - 511 ) ÷ 511] x 100 = -97.06%
Formula
Percentage change = [(15 - 511) / 511] x 100
Subtract the new number by the original number
15 - 511 = -496
-496 ÷ 511 = -0.9706457925636007
-0.9706457925636007 x 100 = -97.06%