五年级奥数专题简便运算2页.doc

五年级奥数专题解小例题】例1 用简便方法计算下面各题.(1)(4.87.58.1)(2.42.52.7) 解：(1)解法一：(4.87.58.1)(2.42.52.7)=(487581)(242527)=(12425381)(642539)=(12100381)(610039)=(1281)(69)=(2699)(69)=29=18解法二：(4.87.58.1)(2.42.52.7)=(4.82.4)(7.52.5)(8.12.7)=233=18(2)0.1250.250.564解法一：0.1250.250.564=0.1250.250.5(248)=(0.1258)(0.254)(0.52)=111=1解法二：0.1250.250.564=0.1