23.27% is the change from 666 to 821
Calculation steps:
[( 821 - 666 ) ÷ 666] x 100 = 23.27%
Formula
Percentage change = [(821 - 666) / 666] x 100
Subtract the new number by the original number
821 - 666 = 155
155 ÷ 666 = 0.23273273273273273
0.23273273273273273 x 100 = 23.27%