题目内容
简算.
23× | ×40-÷ | ×46.7+52.3×+ | (+)×17×25. |
解:(1)23×,
=(22+1)×,
=22×+1×,
=13+,
=13;
(2)×40-÷,
=×40-×40,
=(-)×40,
=×40,
=5;
(3)×46.7+52.3×+,
=×(46.7+52.3+1),
=×100,
=75;
(4)(+)×17×25,
=(+)×(17×25),
=(×17×25)+(×25×17),
=(4×25)+(1×17),
=100+17,
=117.
分析:(1)先把23分解成22+1,再运用乘法分配律简算;
(2)先把除法变成乘法,再运用乘法分配律简算;
(3)运用乘法分配律简算;
(4)先把17×25结合在一起,再运用乘法分配律简算.
点评:乘法分配律是常用的简便运算的方法,要熟练掌握,灵活运用.
=(22+1)×,
=22×+1×,
=13+,
=13;
(2)×40-÷,
=×40-×40,
=(-)×40,
=×40,
=5;
(3)×46.7+52.3×+,
=×(46.7+52.3+1),
=×100,
=75;
(4)(+)×17×25,
=(+)×(17×25),
=(×17×25)+(×25×17),
=(4×25)+(1×17),
=100+17,
=117.
分析:(1)先把23分解成22+1,再运用乘法分配律简算;
(2)先把除法变成乘法,再运用乘法分配律简算;
(3)运用乘法分配律简算;
(4)先把17×25结合在一起,再运用乘法分配律简算.
点评:乘法分配律是常用的简便运算的方法,要熟练掌握,灵活运用.
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