WEBVTT

99:59:59.999 --> 99:59:59.999
18

99:59:59.999 --> 99:59:59.999
27+5=32

99:59:59.999 --> 99:59:59.999
32

99:59:59.999 --> 99:59:59.999
54+1=55

99:59:59.999 --> 99:59:59.999
55

99:59:59.999 --> 99:59:59.999
9×3=27

99:59:59.999 --> 99:59:59.999
9×3=？

99:59:59.999 --> 99:59:59.999
9×6=54

99:59:59.999 --> 99:59:59.999
上边还有进位3

99:59:59.999 --> 99:59:59.999
再加3得66

99:59:59.999 --> 99:59:59.999
另一个6

99:59:59.999 --> 99:59:59.999
大家还记得住吧

99:59:59.999 --> 99:59:59.999
希望大家能有所收获

99:59:59.999 --> 99:59:59.999
得18

99:59:59.999 --> 99:59:59.999
得63

99:59:59.999 --> 99:59:59.999
得63以后

99:59:59.999 --> 99:59:59.999
得66258

99:59:59.999 --> 99:59:59.999
换一个颜色

99:59:59.999 --> 99:59:59.999
没地方再写

99:59:59.999 --> 99:59:59.999
然后 9×6

99:59:59.999 --> 99:59:59.999
然后9×7

99:59:59.999 --> 99:59:59.999
直接写在这就行了

99:59:59.999 --> 99:59:59.999
这写6

99:59:59.999 --> 99:59:59.999
那么7362×9

00:00:00.530 --> 00:00:01.674
如果之前的练习你都做了

00:00:01.674 --> 00:00:04.729
并且已经记住了乘法表

00:00:04.729 --> 00:00:08.785
那么你应该有这种感觉

00:00:08.785 --> 00:00:11.058
可能自己已经可以解决任何乘法问题了！

00:00:11.058 --> 00:00:12.699
你只需要记住--

00:00:12.699 --> 00:00:14.340
怎么说呢--

00:00:14.350 --> 00:00:15.836
记住运算的一般步骤就可以了

00:00:15.836 --> 00:00:17.760
但是我不是要教大家做题步骤

00:00:17.760 --> 00:00:20.280
而是这种运算的本质和原理

00:00:20.280 --> 00:00:23.420
先来做一些

00:00:23.420 --> 00:00:30.119
你可能觉得自己不会的题目吧

00:00:30.119 --> 00:00:31.865
16×9

00:00:31.865 --> 00:00:32.858
16乘以9

00:00:32.858 --> 00:00:36.004
你可以会说

00:00:36.004 --> 00:00:38.790
老师 我没有记住16的乘法表

00:00:38.790 --> 00:00:41.214
不可能会做这个题

00:00:41.214 --> 00:00:43.294
但是我要告诉你的是

00:00:43.294 --> 00:00:45.262
你一定会做！

00:00:45.262 --> 00:00:46.532
因为我们可以把这个问题分解成

00:00:46.532 --> 00:00:49.710
你会做的题目

00:00:49.710 --> 00:00:52.240
到底怎么做呢？

00:00:52.250 --> 00:00:54.820
首先是9乘以这个数的个位

00:00:54.820 --> 00:00:56.760
9×6

00:00:56.770 --> 00:01:01.090
这个大家肯定都会的

00:01:01.100 --> 00:01:03.380
我写在这边

00:01:03.380 --> 00:01:05.861
9×6=54

00:01:05.861 --> 00:01:08.975
知道乘法表就可以得出来

00:01:08.975 --> 00:01:11.935
那么要写下54来

00:01:11.935 --> 00:01:13.710
但是只能把4写在个位这里

00:01:13.710 --> 00:01:17.004
5是进位

00:01:17.004 --> 00:01:19.755
这就是运算的步骤

00:01:19.755 --> 00:01:21.113
在做加法时

00:01:21.128 --> 00:01:24.113
如果产生了大于9的数

00:01:24.113 --> 00:01:28.429
就要进位

00:01:28.429 --> 00:01:29.329
这种运算就是进位 没什么别的描述方法了

00:01:29.329 --> 00:01:31.158
然后9×1

00:01:31.158 --> 00:01:33.490
9乘以1

00:01:33.500 --> 00:01:35.650
这个很简单

00:01:35.650 --> 00:01:38.670
9×1=9

00:01:38.680 --> 00:01:40.740
任何数乘以1都等于本身

00:01:40.750 --> 00:01:45.144
但是上边还有个进位5

00:01:45.144 --> 00:01:47.102
9×1=9

00:01:47.102 --> 00:01:50.160
还要再加上5

00:01:50.160 --> 00:01:55.638
所以再加5

00:01:55.638 --> 00:01:57.702
得到什么呢？

00:01:57.702 --> 00:01:59.689
9×1+5

00:01:59.689 --> 00:02:00.590
得14

00:02:00.590 --> 00:02:04.180
我写在这里

00:02:04.180 --> 00:02:06.534
14

00:02:06.534 --> 00:02:08.440
这样就得出结果了

00:02:08.440 --> 00:02:12.260
16×9=144

00:02:12.260 --> 00:02:14.655
如果你一直记到12的乘法表的话

00:02:14.655 --> 00:02:17.499
应该要注意到144=12×12

00:02:17.499 --> 00:02:19.220
不过只知道9×6和9×1

00:02:19.220 --> 00:02:20.540
也可以解出这个难题

00:02:20.550 --> 00:02:22.160
现在你可能说 老师

00:02:22.160 --> 00:02:25.150
这不过是你耍的一个小把戏

00:02:25.150 --> 00:02:27.920
这怎么可能呢？是为什么？

00:02:27.930 --> 00:02:32.870
大家应该经常这么问

00:02:32.870 --> 00:02:34.980
不要只是被动的接受我说的话

00:02:34.990 --> 00:02:36.930
不要死记公式方法

00:02:36.930 --> 00:02:37.865
生搬硬套

00:02:37.865 --> 00:02:40.760
那么 我换个写法给大家解释一下

00:02:40.770 --> 00:02:44.190
可以把16改成10--

00:02:44.190 --> 00:02:46.960
在这里写吧

00:02:46.960 --> 00:02:50.830
16=10+6

00:02:50.840 --> 00:02:52.810
把16拆开了

00:02:52.810 --> 00:02:56.490
当然9也可以拆

00:02:56.500 --> 00:02:59.580
不过只是一位数 可以留着

00:02:59.590 --> 00:03:00.990
就像这样

00:03:00.990 --> 00:03:02.880
下面来看看这个问题究竟怎么回事

00:03:02.880 --> 00:03:04.390
在这写一个乘法号

00:03:04.400 --> 00:03:06.050
首先要用9乘以6

00:03:06.060 --> 00:03:08.310
你可能要问

00:03:08.310 --> 00:03:10.707
老师你为什么要这么分16呢？

00:03:10.707 --> 00:03:11.838
其实我是把16的个位和

00:03:11.838 --> 00:03:15.400
十位拆开

00:03:15.400 --> 00:03:16.528
这个从右数的第二列

00:03:16.528 --> 00:03:21.740
这可不是个1 而是10

00:03:21.750 --> 00:03:25.060
16左边的1是10 所以拆成10+6

00:03:25.060 --> 00:03:27.270
这就是这么拆的原因

00:03:27.280 --> 00:03:29.340
好 现在来运算

00:03:29.340 --> 00:03:30.580
跟刚刚的方法一样

00:03:30.590 --> 00:03:32.847
9×6--

00:03:32.847 --> 00:03:35.410
写下来

00:03:35.410 --> 00:03:36.773
9×6=54

00:03:36.773 --> 00:03:39.537
但是这里不写54

00:03:39.537 --> 00:03:40.685
而是拆成50+4

00:03:40.685 --> 00:03:42.166
9×6=50+4

00:03:42.166 --> 00:03:46.730
好了 这一列代表个位

00:03:46.740 --> 00:03:48.330
画一条虚线来分隔

00:03:48.340 --> 00:03:50.470
这边是个位

00:03:50.470 --> 00:03:52.370
只能写一个4

00:03:52.380 --> 00:03:55.854
但还要写50

00:03:55.854 --> 00:03:57.830
要找个地方写50

00:03:57.840 --> 00:03:59.827
惯例是--

00:03:59.827 --> 00:04:01.710
至少我学的是这样--

00:04:01.710 --> 00:04:03.479
把50写在这上边

00:04:03.479 --> 00:04:06.620
当然也可以写在下面

00:04:06.620 --> 00:04:09.952
只要记得

00:04:09.952 --> 00:04:14.853
运算时得到十位有个50就行

00:04:14.853 --> 00:04:16.278
可以把50写在这

00:04:16.278 --> 00:04:18.860
跟第一个题做的一样

00:04:18.870 --> 00:04:20.430
只写一个5

00:04:20.430 --> 00:04:22.831
刚刚就是只写了一个5

00:04:22.831 --> 00:04:25.043
因为这个5是在十位的

00:04:25.043 --> 00:04:26.860
实际上代表的是50

00:04:26.870 --> 00:04:28.709
十位的1就是10

00:04:28.709 --> 00:04:33.850
不过现在我要写50

00:04:33.850 --> 00:04:35.850
这样大家看的比较清楚 就代表50 或者10

00:04:35.850 --> 00:04:39.010
然后 9×10=？

00:04:39.010 --> 00:04:40.543
9×10

00:04:40.543 --> 00:04:45.620
这个我们也记过的

00:04:45.620 --> 00:04:50.553
任何数乘以10就是这个数后边添个0

00:04:50.553 --> 00:04:51.872
得90

00:04:51.872 --> 00:04:53.406
9×10=90

00:04:53.406 --> 00:04:54.925
再加50

00:04:54.925 --> 00:04:57.342
90+50

00:04:57.342 --> 00:04:58.882
等于多少呢？

00:04:58.882 --> 00:05:00.250
是140

00:05:00.250 --> 00:05:02.180
9×10=90

00:05:02.190 --> 00:05:06.125
90+50=140

00:05:06.125 --> 00:05:07.230
为了跟之前写的保持一致

00:05:07.240 --> 00:05:09.020
可以把140写成100+40

00:05:09.020 --> 00:05:13.207
所以我们要把40放在这里

00:05:13.207 --> 00:05:16.154
百位进1

00:05:16.154 --> 00:05:19.440
但是100不知道放在哪

00:05:19.450 --> 00:05:22.001
可以写在这

00:05:22.001 --> 00:05:24.860
可以--

00:05:24.870 --> 00:05:35.155
也可以写在这

00:05:35.155 --> 00:05:37.774
写在这里

00:05:37.774 --> 00:05:39.255
很多地方可以写

00:05:39.255 --> 00:05:40.510
这个100

00:05:40.510 --> 00:05:41.800
但是最重要的一点不要忘记

00:05:41.800 --> 00:05:42.820
这个一百是在百位上

00:05:42.820 --> 00:05:47.130
分隔线我刚没画

00:05:47.140 --> 00:05:49.950
这样再写一个100

00:05:49.950 --> 00:05:52.840
得到是100+40+4

00:05:52.850 --> 00:05:54.820
即144

00:05:54.820 --> 00:05:56.000
希望大家能听懂

00:05:56.010 --> 00:05:59.560
再来多做几个题

00:05:59.560 --> 00:06:02.100
多看例题是很重要的

00:06:02.110 --> 00:06:04.184
计算55×8

00:06:04.184 --> 00:06:07.170
55×8

00:06:07.180 --> 00:06:08.183
差不多的例题

00:06:08.183 --> 00:06:11.910
要用8开始乘

00:06:11.920 --> 00:06:14.714
8×5

00:06:14.714 --> 00:06:18.830
我先写下来

00:06:18.830 --> 00:06:27.260
8×5=40

00:06:27.270 --> 00:06:28.950
把0写在这

00:06:28.950 --> 00:06:31.240
进位4

00:06:31.250 --> 00:06:33.050
然后又是8×5

00:06:33.050 --> 00:06:36.550
还是40

00:06:36.550 --> 00:06:40.470
不过再加上进位4 是44

00:06:40.470 --> 00:06:43.590
代表的是440

00:06:43.600 --> 00:06:46.540
你可以像我上个题一样

00:06:46.550 --> 00:06:49.750
把55拆成50+5再分别乘以8

00:06:49.750 --> 00:06:52.045
不过做的题多了

00:06:52.045 --> 00:06:53.480
应该大家会习惯这么运算的

00:06:53.490 --> 00:06:55.580
再做一个--

00:06:55.580 --> 00:06:57.960
换个颜色

00:06:57.970 --> 00:07:01.790
浅红色

00:07:01.800 --> 00:07:02.562
用78乘以--

00:07:02.562 --> 00:07:06.175
乘以7

00:07:06.175 --> 00:07:08.190
8×7

00:07:08.190 --> 00:07:09.680
8×7=56

00:07:09.680 --> 00:07:13.810
写下来--这又是一个新题

00:07:13.820 --> 00:07:16.804
8×7=56

00:07:16.804 --> 00:07:25.865
把6写在下边 进位5写在上边

00:07:25.865 --> 00:07:27.600
7×7=49

00:07:27.600 --> 00:07:31.390
7乘以7得49

00:07:31.390 --> 00:07:33.070
还要加上边的5

00:07:33.080 --> 00:07:35.287
再加上5

00:07:35.287 --> 00:07:36.847
49+5=？

00:07:36.847 --> 00:07:38.360
是54

00:07:38.370 --> 00:07:40.330
7×7=49

00:07:40.330 --> 00:07:42.950
49+5=54

00:07:42.950 --> 00:07:46.240
得546

00:07:46.250 --> 00:07:47.535
不久前你可能还觉得

00:07:47.535 --> 00:07:49.120
光用1-12的乘法表

00:07:49.120 --> 00:07:50.150
肯定求不出78的乘法表

00:07:50.160 --> 00:07:51.940
但大家可以看到过程其实非常简单

00:07:51.940 --> 00:07:54.510
再多做几个

00:07:54.520 --> 00:07:57.760
一直算到不能再算为止

00:07:57.760 --> 00:07:59.135
算到精疲力竭为止

00:07:59.135 --> 00:08:04.147
89×3

00:08:04.147 --> 00:08:06.689
89×3=？

00:08:06.689 --> 00:08:09.177
3×9=27

00:08:09.177 --> 00:08:20.374
7写在个位

00:08:20.374 --> 00:08:23.178
向十位进位2

00:08:23.178 --> 00:08:24.712
因为27=20+7

00:08:24.712 --> 00:08:27.992
两个10就是20

00:08:27.992 --> 00:08:29.562
加7是27

00:08:29.562 --> 00:08:32.480
然后3×8=24

00:08:32.480 --> 00:08:34.446
3×8=24

00:08:34.446 --> 00:08:35.870
上边还有一个2的进位

00:08:35.870 --> 00:08:37.870
还要再加2

00:08:37.880 --> 00:08:39.430
得26

00:08:39.440 --> 00:08:41.670
3×8=24

00:08:41.670 --> 00:08:45.080
24+2=26

00:08:45.090 --> 00:08:48.640
结果是267

00:08:48.640 --> 00:08:49.820
再做一个

00:08:49.830 --> 00:08:52.184
不过我要加难度了

00:08:52.184 --> 00:08:54.397
在你觉得

00:08:54.397 --> 00:08:56.742
这些都会做的时候

00:08:56.742 --> 00:08:58.530
我再出一个能难到你的！

00:08:58.530 --> 00:09:02.178
239×6

00:09:02.178 --> 00:09:03.682
本来是要做

00:09:03.682 --> 00:09:10.160
两位数乘一位数的视频的

00:09:10.160 --> 00:09:10.902
不过这题也是告诉大家

00:09:10.902 --> 00:09:13.788
不管是几位数去乘一个一位数

00:09:13.788 --> 00:09:14.645
你都是可以做的

00:09:14.645 --> 00:09:18.360
步骤大同小异

00:09:18.360 --> 00:09:19.973
大家可以猜一猜这个要怎么做

00:09:19.973 --> 00:09:21.400
6×9=？

00:09:21.400 --> 00:09:24.490
在这里写

00:09:24.500 --> 00:09:27.830
6×9

00:09:27.830 --> 00:09:32.200
这个之前算过了

00:09:32.200 --> 00:09:34.140
54

00:09:34.140 --> 00:09:36.390
把4写在这

00:09:36.400 --> 00:09:38.790
5放在十位

00:09:38.800 --> 00:09:41.490
因为这个54中的5就是5个10

00:09:41.490 --> 00:09:43.800
好

00:09:43.800 --> 00:09:46.380
然后是6×3

00:09:46.380 --> 00:09:49.228
6×3

00:09:49.228 --> 00:09:52.610
得18

00:09:52.610 --> 00:09:57.350
上边还有一个5

00:09:57.350 --> 00:10:01.140
还要加5

00:10:01.140 --> 00:10:02.290
18+5=？

00:10:02.300 --> 00:10:03.490
6×3=18 18+5=23

00:10:03.500 --> 00:10:06.710
澄清一点

00:10:06.710 --> 00:10:08.320
并不是用6×3+5

00:10:08.320 --> 00:10:09.770
你看

00:10:09.770 --> 00:10:12.251
在这个问题里

00:10:12.251 --> 00:10:15.025
3其实是30

00:10:15.025 --> 00:10:17.365
只不过写的是3

00:10:17.370 --> 00:10:18.620
但这其实是6×30+50

00:10:18.620 --> 00:10:20.120
因为39的3是3个10 或者是30

00:10:20.130 --> 00:10:21.830
那么

00:10:21.840 --> 00:10:23.500
虽然这里说6×3=18

00:10:23.500 --> 00:10:25.497
18+5=23

00:10:25.497 --> 00:10:26.740
实际得到的其实是230

00:10:26.740 --> 00:10:29.090
把3放在十位

00:10:29.090 --> 00:10:35.210
我换个颜色来写

00:10:35.210 --> 00:10:38.197
用个跟上边不一样的

00:10:38.197 --> 00:10:40.980
结果是23

00:10:40.980 --> 00:10:42.869
把3放在十位

00:10:42.869 --> 00:10:46.615
向百位进2 写上边

00:10:46.615 --> 00:10:53.058
差不多就做完了 再乘最后一次

00:10:53.058 --> 00:10:53.814
6×2

00:10:53.814 --> 00:10:56.210
这个很简单

00:10:56.220 --> 00:10:58.320
得12

00:10:58.320 --> 00:10:59.900
但是上边还有进位2

00:10:59.900 --> 00:11:01.260
所以还要再加2

00:11:01.260 --> 00:11:03.380
+2

00:11:03.390 --> 00:11:06.202
等于什么呢？

00:11:06.202 --> 00:11:08.130
12+2=14

00:11:08.145 --> 00:11:10.125
写4

00:11:10.130 --> 00:11:13.960
6×2=12

00:11:13.970 --> 00:11:18.675
12+2=14

00:11:18.675 --> 00:11:20.841
把4写在下边

00:11:20.841 --> 00:11:23.254
如果这里还有更高位的话就写在上边

00:11:23.270 --> 00:11:27.140
但是没有了

00:11:27.140 --> 00:11:34.370
所以直接写在这就可以了

00:11:34.370 --> 00:11:36.348
239×6

00:11:36.348 --> 00:11:38.961
=1434

00:11:38.961 --> 00:11:40.707
再做一个

00:11:40.710 --> 00:11:44.158
需要清一些空间出来

00:11:44.158 --> 00:11:47.350
既然已经增加难度了

00:11:47.360 --> 00:11:50.460
下面来做一个四位数的吧

00:11:50.460 --> 00:11:52.032
7362×--

00:11:52.032 --> 00:11:54.552
难点的--9

00:11:54.552 --> 00:11:56.872
9×2=？

00:11:56.872 --> 00:12:00.494
我就不再写在旁边了

00:12:00.494 --> 00:12:05.024
大家应该已经明白这个套路了

00:12:05.024 --> 00:12:07.200
9×2=？