1989+1988+1987-1986-1985-1984+1983+1982+1981-.+9+8+7-6-5-4+3+2+1
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/30 05:59:21
![1989+1988+1987-1986-1985-1984+1983+1982+1981-.+9+8+7-6-5-4+3+2+1](/uploads/image/z/66655-55-5.jpg?t=1989%EF%BC%8B1988%EF%BC%8B1987%EF%BC%8D1986%EF%BC%8D1985%EF%BC%8D1984%EF%BC%8B1983%EF%BC%8B1982%EF%BC%8B1981%EF%BC%8D.%2B9%EF%BC%8B8%EF%BC%8B7%EF%BC%8D6%EF%BC%8D5-4%EF%BC%8B3%EF%BC%8B2%EF%BC%8B1)
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1989+1988+1987-1986-1985-1984+1983+1982+1981-.+9+8+7-6-5-4+3+2+1
1989+1988+1987-1986-1985-1984+1983+1982+1981-.+9+8+7-6-5-4+3+2+1
1989+1988+1987-1986-1985-1984+1983+1982+1981-.+9+8+7-6-5-4+3+2+1
1989/6=331.3
每六个数1组,和为3*3=9
1989+1988+1987-1986-1985-1984+1983+1982+1981-.+9+8+7-6-5-4+3+2+1
=(1989+1988+1987-1986-1985-1984)+(1983+1982+1981-1980-1979-1978)+.+(9+8+7-6-5-4)+3+2+1
=331*9+6
=2979+6
=2985