怎么简便怎么算 1/1×1/2+1/2×1/3+1/3×1/4+1/4×1/5+……1/49×1/50

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怎么简便怎么算 1/1×1/2+1/2×1/3+1/3×1/4+1/4×1/5+……1/49×1/50

1/1×1/2+1/2×1/3+1/3×1/4+1/4×1/5+……1/49×1/50
=(1-1/2)+(1/2-1/3)+.+(1/49-1/50)
=1-1/50
=49/50