题干

计算:8.01×1.25+8.02×1.24+8.03×1.23+8.04×1.22+8.05×1.21的整数部分.

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答案(点此获取答案解析)

解:当两个数的和不变时,两数越接近(即差越小)它们积越大,

所以8.05×1.21<8.04×1.22<8.03×1.23<8.02×1.24<8.01×1.25,

因为8.01×1.25+8.02×1.24+8.03×1.23+8.04×1.22+8.05×1.21<8.01×1.25×5<8×1.25×5=50,

8.01×1.25+8.02×1.24+8.03×1.23+8.04×1.22+8.05×1.21>8×(1.21+1.22+1.23+1.24+1