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问题: 分数问题

1/1*2+2/1*2*3+3/1*2*3*4+……+9/1*2*3*4*5*6*7*8*9*10

解答:

1/(1*2)+2/(1*2*3)+3/(1*2*3*4)+……+9/(1*2*3*4*5*6*7*8*9*10)
=(2-1)/(1*2)+(3-1)/(1*2*3)+(4-1)/(1*2*3*4)
+……+(10-1)/(1*2*3*……*9*10)
=[1-1/(1*2)]+[1/(1*2)-1/(1*2*3)]+[1/(1*2*3)-1/(1*2*3*4)
+……+[1/(1*2*3*……*9)-1/(1*2*3*……*9*10)]
=1-1/(1*2*3*4*……*10)
=1-1/3628800
=3628799/3628800.