64.52% is the change from 31 to 51
Calculation steps:
[( 51 - 31 ) ÷ 31] x 100 = 64.52%
Formula
Percentage change = [(51 - 31) / 31] x 100
Subtract the new number by the original number
51 - 31 = 20
20 ÷ 31 = 0.6451612903225806
0.6451612903225806 x 100 = 64.52%