Question

比较两个数的大小
A=5.4321×1.2345，B=5.4322×1.2344．A

＞

B．

Answer 1

分析：结合乘法分配律，原式可化为：A=5.4321×1.2345=5.4321×（1.2344+0.0001）=5.4321×1.2344+5.4321×0.0001；B=5.4322×1.2344=（5.4321+0.0001）×1.2344=5.4321×1.2344+1.2344×0.0001，由此可以比较大小．

解答：解：A=5.4321×1.2345=5.4321×（1.2344+0.0001）=5.4321×1.2344+5.4321×0.0001，
B=5.4322×1.2344=（5.4321+0.0001）×1.2344=5.4321×1.2344+1.2344×0.0001，
因为5.4321×0.0001＞1.2344×0.0001，
所以5.4321×1.2344+5.4321×0.0001＞5.4321×1.2344+1.2344×0.0001，
即A＞B
故答案为：＞．

点评：此类比较大小的题目关键是想法把式子中的因数化为相同的数，要运用拆数的技巧并结合乘法分配律灵活进行．