25.76% is the change from 660 to 830
Calculation steps:
[( 830 - 660 ) ÷ 660] x 100 = 25.76%
Formula
Percentage change = [(830 - 660) / 660] x 100
Subtract the new number by the original number
830 - 660 = 170
170 ÷ 660 = 0.25757575757575757
0.25757575757575757 x 100 = 25.76%