51.85% is the change from 81 to 123
Calculation steps:
[( 123 - 81 ) ÷ 81] x 100 = 51.85%
Formula
Percentage change = [(123 - 81) / 81] x 100
Subtract the new number by the original number
123 - 81 = 42
42 ÷ 81 = 0.5185185185185185
0.5185185185185185 x 100 = 51.85%