7.78% is the change from 270 to 291
Calculation steps:
[( 291 - 270 ) ÷ 270] x 100 = 7.78%
Formula
Percentage change = [(291 - 270) / 270] x 100
Subtract the new number by the original number
291 - 270 = 21
21 ÷ 270 = 0.07777777777777778
0.07777777777777778 x 100 = 7.78%