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．

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+1.25）=49.2，
所以8.01×1.25+8.02×1.24+8.03×1.23+8.04×1.22+8.05×1.21的整数部分是49．
答：8.01×1.25+8.02×1.24+8.03×1.23+8.04×1.22+8.05×1.21的整数部分是49．