61.3% is the change from 509 to 821
Calculation steps:
[( 821 - 509 ) ÷ 509] x 100 = 61.3%
Formula
Percentage change = [(821 - 509) / 509] x 100
Subtract the new number by the original number
821 - 509 = 312
312 ÷ 509 = 0.6129666011787819
0.6129666011787819 x 100 = 61.3%