做出这到题1 1/2-2 5/6+3 1/12-4 19/20+5 1/30-6 41/42+7 1/56-8 71/72+9 1/90=

=1 1/2-3+1/6+3 1/12-5+1/20+5 1/30-7+1/42+7 1/56-9+1/72+9 1/90
（1-3+3-5+5-7+7-9+9）+(1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90)
=1+(1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10)
=1+1-1/10
=1 9/10

1.9

我用VBS算得，保证对！

dim b
b=1+1/2-2-5/6+3+1/12-4-19/20+5+1/30-6-41/42+7+1/56-8-71/72+9+1/90
msgbox(b)

除非我电脑坏了。

3/2-17/6+37/12-99/80+151/30+293/42 +393/56-647/72+811/90=27 73/560