首页 > 计算：2000-1990+1980-1970+…+20-10(1-12)(1-13)(1-14)(1-15)…(1-1999)(1-11000)=______．-数学

计算：2000-1990+1980-1970+…+20-10(1-12)(1-13)(1-14)(1-15)…(1-1999)(1-11000)=______．-数学

题目简介

计算：2000-1990+1980-1970+…+20-10(1-12)(1-13)(1-14)(1-15)…(1-1999)(1-11000)=______．-数学

题目详情

计算：
2000-1990+1980-1970+…+20-10
(1-
1
2
)(1-
1
3
)(1-
1
4
)(1-
1
5
)…(1-
1
999
)(1-
1
1000
)
=______．
题型：填空题难度：中档来源：不详

答案

class="stub"2000-1990+1980-1970+…+20+10
(1-class="stub"1
2
)(1-class="stub"1
3
)(1-class="stub"1
4
)(1-class="stub"1
5
)．．(1-class="stub"1
999
)(1-class="stub"1
1000
)

=
(2000-1990)+(1980-1970)+…+(20-10)
class="stub"1
2
．class="stub"2
3
．class="stub"3
4
．class="stub"4
5
．．class="stub"998
999
．class="stub"999
1000

=(
100个10
10+10+10+…+10
)÷class="stub"1
1000
=class="stub"1000
class="stub"1
1000
=1000000．

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