0.11+0.13+0.15+……+0.97+0.99=

原式=(（0.11+0.99）*44)/2
=24.2

0.11+0.13+0.15+……+0.97+0.99
=100(0.11+0.13+0.15+……+0.97+0.99)/100
=(11+13+15+......97+99)/100
=((1+3+5+7+9+11+13+15+......97+99)-(1+3+5+7+9))/100
=(n(n+1)/2-n(n+1))/2/100
=(99*(99+1)/2-9*(9+1)/2)/100
=(99*100/2-9*10/2)/100
=(99*50-9*5)/100
=49.05

0.11+0.13+0.15+.......+0.97+0.99
=（0.11+0.99）*442
=1.1*442
=48.42
=24.2