巧算1/1×2+1/2×3+1/3×4+.1/56×57

题目详情

巧算
1/1×2 +1/2×3+1/3×4+.1/56×57

▼优质解答

答案和解析

1/1×2 +1/2×3+1/3×4+.1/56×57
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+.+(1/56-1/57)
=1-1/2+1/2-1/3+1/3-1/4+.+1/56-1/57
=1-1/57
=56/57

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