65.03% is the change from 509 to 840
Calculation steps:
[( 840 - 509 ) ÷ 509] x 100 = 65.03%
Formula
Percentage change = [(840 - 509) / 509] x 100
Subtract the new number by the original number
840 - 509 = 331
331 ÷ 509 = 0.650294695481336
0.650294695481336 x 100 = 65.03%