-38% is the change from 821 to 509
Calculation steps:
[( 509 - 821 ) ÷ 821] x 100 = -38%
Formula
Percentage change = [(509 - 821) / 821] x 100
Subtract the new number by the original number
509 - 821 = -312
-312 ÷ 821 = -0.3800243605359318
-0.3800243605359318 x 100 = -38%