30.63% is the change from 666 to 870
Calculation steps:
[( 870 - 666 ) ÷ 666] x 100 = 30.63%
Formula
Percentage change = [(870 - 666) / 666] x 100
Subtract the new number by the original number
870 - 666 = 204
204 ÷ 666 = 0.3063063063063063
0.3063063063063063 x 100 = 30.63%