比一比，看谁算的又对又快。143= 125= 20030= 253=492= 10070= 164= 262=153= 172= 30300= 153= Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.估算15119 73149 795 102 60 401 Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.先用个位上的4去乘27, 积的末尾8与因数的个 位对齐。 再用十位上的3去乘27 ，积的末尾1与因数的 十位对齐。最后把两个得数加 起来2 7 3 4 1 0 88 1 9 1 8注意积的末位要与 十位对齐！用哪一 位去乘，积的末尾 就和哪一位对齐。列竖式算一算Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.A BC DEvaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.1.高速公路一期工程全长多少米？2.高速公路二期工程全长多少米？Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.用以前学过的两 位数乘两位数的 竖式试算一下吧 ！我可以估算一下：213200 20015=300021315=高速公路一期工程全长多少米？估算是大约值，不是准确值， 所以不能用这个答案。 Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.用笔算准确：1 0 6 52 1 3 12 1 3 3 1 9 5先用个位上的5去乘213 再用十位上的1去乘2135注意积的末位 要与十位对齐！把所得的积加起来三位数乘两位数与两位数乘两位 数方法类似：先用两位数个位上的数乘三位数，用哪一位去乘，积的末尾就和哪一 位对齐，最后把两次乘得的积相加。小结再用两位数十位上的数乘三位数，Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.高速公路一期工程全长多少米？21315=答：高速公路一期工程全长 3195米。3195（米）Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.2.高速公路二期工程全长多少米？Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.这样列更好：2 6 0 5 22 6 01 2我这样列竖式：26012=高速公路二期工程全长多少米？5 2 0 2 6 0 3 1 2 01 22 63 1 2 03120（米）答： 高速 公路 二期 工程 全长 3120 米。小结：先用0前面的数相乘 ，然后看因数末尾共有几 个0，就在积的末尾添写几 个0。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.3 7 5 1 2 2 4 0 4 5 3 0 9 2 6 说说计算过程!乘数中间有0时计算中应怎么办啊?拓展提升7 5 0 3 7 54 5 0 01 2 0 9 61 0 8 0 01 8 5 46 1 88 0 3 4Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.森 林 医 生7 9 21 3 2 1 61 3 2 9 2 47 2 41 2 4 3 63 7 24 4 4 44 3 81 4 6 2 32 9 23 3 5 8上面的计算对吗? 不对的改正过来。1 3 2 2 1 1 27 4 46 Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.每辆车可以坐40人。公交公司共有这样的 大客车128辆。一共可以坐多少人？128 405120Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.课堂小结通过这一课的学习你有 哪些收获？Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.