209.88% is the change from 81 to 251
Calculation steps:
[( 251 - 81 ) ÷ 81] x 100 = 209.88%
Formula
Percentage change = [(251 - 81) / 81] x 100
Subtract the new number by the original number
251 - 81 = 170
170 ÷ 81 = 2.0987654320987654
2.0987654320987654 x 100 = 209.88%