-49.05% is the change from 999 to 509
Calculation steps:
[( 509 - 999 ) ÷ 999] x 100 = -49.05%
Formula
Percentage change = [(509 - 999) / 999] x 100
Subtract the new number by the original number
509 - 999 = -490
-490 ÷ 999 = -0.4904904904904905
-0.4904904904904905 x 100 = -49.05%