1
99:59:59,999 --> 99:59:59,999
18

2
99:59:59,999 --> 99:59:59,999
27+5=32

3
99:59:59,999 --> 99:59:59,999
32

4
99:59:59,999 --> 99:59:59,999
54+1=55

5
99:59:59,999 --> 99:59:59,999
55

6
99:59:59,999 --> 99:59:59,999
9×3=27

7
99:59:59,999 --> 99:59:59,999
9×3=？

8
99:59:59,999 --> 99:59:59,999
9×6=54

9
99:59:59,999 --> 99:59:59,999
上边还有进位3

10
99:59:59,999 --> 99:59:59,999
再加3得66

11
99:59:59,999 --> 99:59:59,999
另一个6

12
99:59:59,999 --> 99:59:59,999
大家还记得住吧

13
99:59:59,999 --> 99:59:59,999
希望大家能有所收获

14
99:59:59,999 --> 99:59:59,999
得18

15
99:59:59,999 --> 99:59:59,999
得63

16
99:59:59,999 --> 99:59:59,999
得63以后

17
99:59:59,999 --> 99:59:59,999
得66258

18
99:59:59,999 --> 99:59:59,999
换一个颜色

19
99:59:59,999 --> 99:59:59,999
没地方再写

20
99:59:59,999 --> 99:59:59,999
然后 9×6

21
99:59:59,999 --> 99:59:59,999
然后9×7

22
99:59:59,999 --> 99:59:59,999
直接写在这就行了

23
99:59:59,999 --> 99:59:59,999
这写6

24
99:59:59,999 --> 99:59:59,999
那么7362×9

25
00:00:00,530 --> 00:00:01,674
如果之前的练习你都做了

26
00:00:01,674 --> 00:00:04,729
并且已经记住了乘法表

27
00:00:04,729 --> 00:00:08,785
那么你应该有这种感觉

28
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！

29
00:00:11,058 --> 00:00:12,699
你只需要记住--

30
00:00:12,699 --> 00:00:14,340
怎么说呢--

31
00:00:14,350 --> 00:00:15,836
记住运算的一般步骤就可以了

32
00:00:15,836 --> 00:00:17,760
但是我不是要教大家做题步骤

33
00:00:17,760 --> 00:00:20,280
而是这种运算的本质和原理

34
00:00:20,280 --> 00:00:23,420
先来做一些

35
00:00:23,420 --> 00:00:30,119
你可能觉得自己不会的题目吧

36
00:00:30,119 --> 00:00:31,865
16×9

37
00:00:31,865 --> 00:00:32,858
16乘以9

38
00:00:32,858 --> 00:00:36,004
你可以会说

39
00:00:36,004 --> 00:00:38,790
老师 我没有记住16的乘法表

40
00:00:38,790 --> 00:00:41,214
不可能会做这个题

41
00:00:41,214 --> 00:00:43,294
但是我要告诉你的是

42
00:00:43,294 --> 00:00:45,262
你一定会做！

43
00:00:45,262 --> 00:00:46,532
因为我们可以把这个问题分解成

44
00:00:46,532 --> 00:00:49,710
你会做的题目

45
00:00:49,710 --> 00:00:52,240
到底怎么做呢？

46
00:00:52,250 --> 00:00:54,820
首先是9乘以这个数的个位

47
00:00:54,820 --> 00:00:56,760
9×6

48
00:00:56,770 --> 00:01:01,090
这个大家肯定都会的

49
00:01:01,100 --> 00:01:03,380
我写在这边

50
00:01:03,380 --> 00:01:05,861
9×6=54

51
00:01:05,861 --> 00:01:08,975
知道乘法表就可以得出来

52
00:01:08,975 --> 00:01:11,935
那么要写下54来

53
00:01:11,935 --> 00:01:13,710
但是只能把4写在个位这里

54
00:01:13,710 --> 00:01:17,004
5是进位

55
00:01:17,004 --> 00:01:19,755
这就是运算的步骤

56
00:01:19,755 --> 00:01:21,113
在做加法时

57
00:01:21,128 --> 00:01:24,113
如果产生了大于9的数

58
00:01:24,113 --> 00:01:28,429
就要进位

59
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

60
00:01:29,329 --> 00:01:31,158
然后9×1

61
00:01:31,158 --> 00:01:33,490
9乘以1

62
00:01:33,500 --> 00:01:35,650
这个很简单

63
00:01:35,650 --> 00:01:38,670
9×1=9

64
00:01:38,680 --> 00:01:40,740
任何数乘以1都等于本身

65
00:01:40,750 --> 00:01:45,144
但是上边还有个进位5

66
00:01:45,144 --> 00:01:47,102
9×1=9

67
00:01:47,102 --> 00:01:50,160
还要再加上5

68
00:01:50,160 --> 00:01:55,638
所以再加5

69
00:01:55,638 --> 00:01:57,702
得到什么呢？

70
00:01:57,702 --> 00:01:59,689
9×1+5

71
00:01:59,689 --> 00:02:00,590
得14

72
00:02:00,590 --> 00:02:04,180
我写在这里

73
00:02:04,180 --> 00:02:06,534
14

74
00:02:06,534 --> 00:02:08,440
这样就得出结果了

75
00:02:08,440 --> 00:02:12,260
16×9=144

76
00:02:12,260 --> 00:02:14,655
如果你一直记到12的乘法表的话

77
00:02:14,655 --> 00:02:17,499
应该要注意到144=12×12

78
00:02:17,499 --> 00:02:19,220
不过只知道9×6和9×1

79
00:02:19,220 --> 00:02:20,540
也可以解出这个难题

80
00:02:20,550 --> 00:02:22,160
现在你可能说 老师

81
00:02:22,160 --> 00:02:25,150
这不过是你耍的一个小把戏

82
00:02:25,150 --> 00:02:27,920
这怎么可能呢？是为什么？

83
00:02:27,930 --> 00:02:32,870
大家应该经常这么问

84
00:02:32,870 --> 00:02:34,980
不要只是被动的接受我说的话

85
00:02:34,990 --> 00:02:36,930
不要死记公式方法

86
00:02:36,930 --> 00:02:37,865
生搬硬套

87
00:02:37,865 --> 00:02:40,760
那么 我换个写法给大家解释一下

88
00:02:40,770 --> 00:02:44,190
可以把16改成10--

89
00:02:44,190 --> 00:02:46,960
在这里写吧

90
00:02:46,960 --> 00:02:50,830
16=10+6

91
00:02:50,840 --> 00:02:52,810
把16拆开了

92
00:02:52,810 --> 00:02:56,490
当然9也可以拆

93
00:02:56,500 --> 00:02:59,580
不过只是一位数 可以留着

94
00:02:59,590 --> 00:03:00,990
就像这样

95
00:03:00,990 --> 00:03:02,880
下面来看看这个问题究竟怎么回事

96
00:03:02,880 --> 00:03:04,390
在这写一个乘法号

97
00:03:04,400 --> 00:03:06,050
首先要用9乘以6

98
00:03:06,060 --> 00:03:08,310
你可能要问

99
00:03:08,310 --> 00:03:10,707
老师你为什么要这么分16呢？

100
00:03:10,707 --> 00:03:11,838
其实我是把16的个位和

101
00:03:11,838 --> 00:03:15,400
十位拆开

102
00:03:15,400 --> 00:03:16,528
这个从右数的第二列

103
00:03:16,528 --> 00:03:21,740
这可不是个1 而是10

104
00:03:21,750 --> 00:03:25,060
16左边的1是10 所以拆成10+6

105
00:03:25,060 --> 00:03:27,270
这就是这么拆的原因

106
00:03:27,280 --> 00:03:29,340
好 现在来运算

107
00:03:29,340 --> 00:03:30,580
跟刚刚的方法一样

108
00:03:30,590 --> 00:03:32,847
9×6--

109
00:03:32,847 --> 00:03:35,410
写下来

110
00:03:35,410 --> 00:03:36,773
9×6=54

111
00:03:36,773 --> 00:03:39,537
但是这里不写54

112
00:03:39,537 --> 00:03:40,685
而是拆成50+4

113
00:03:40,685 --> 00:03:42,166
9×6=50+4

114
00:03:42,166 --> 00:03:46,730
好了 这一列代表个位

115
00:03:46,740 --> 00:03:48,330
画一条虚线来分隔

116
00:03:48,340 --> 00:03:50,470
这边是个位

117
00:03:50,470 --> 00:03:52,370
只能写一个4

118
00:03:52,380 --> 00:03:55,854
但还要写50

119
00:03:55,854 --> 00:03:57,830
要找个地方写50

120
00:03:57,840 --> 00:03:59,827
惯例是--

121
00:03:59,827 --> 00:04:01,710
至少我学的是这样--

122
00:04:01,710 --> 00:04:03,479
把50写在这上边

123
00:04:03,479 --> 00:04:06,620
当然也可以写在下面

124
00:04:06,620 --> 00:04:09,952
只要记得

125
00:04:09,952 --> 00:04:14,853
运算时得到十位有个50就行

126
00:04:14,853 --> 00:04:16,278
可以把50写在这

127
00:04:16,278 --> 00:04:18,860
跟第一个题做的一样

128
00:04:18,870 --> 00:04:20,430
只写一个5

129
00:04:20,430 --> 00:04:22,831
刚刚就是只写了一个5

130
00:04:22,831 --> 00:04:25,043
因为这个5是在十位的

131
00:04:25,043 --> 00:04:26,860
实际上代表的是50

132
00:04:26,870 --> 00:04:28,709
十位的1就是10

133
00:04:28,709 --> 00:04:33,850
不过现在我要写50

134
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

135
00:04:35,850 --> 00:04:39,010
然后 9×10=？

136
00:04:39,010 --> 00:04:40,543
9×10

137
00:04:40,543 --> 00:04:45,620
这个我们也记过的

138
00:04:45,620 --> 00:04:50,553
任何数乘以10就是这个数后边添个0

139
00:04:50,553 --> 00:04:51,872
得90

140
00:04:51,872 --> 00:04:53,406
9×10=90

141
00:04:53,406 --> 00:04:54,925
再加50

142
00:04:54,925 --> 00:04:57,342
90+50

143
00:04:57,342 --> 00:04:58,882
等于多少呢？

144
00:04:58,882 --> 00:05:00,250
是140

145
00:05:00,250 --> 00:05:02,180
9×10=90

146
00:05:02,190 --> 00:05:06,125
90+50=140

147
00:05:06,125 --> 00:05:07,230
为了跟之前写的保持一致

148
00:05:07,240 --> 00:05:09,020
可以把140写成100+40

149
00:05:09,020 --> 00:05:13,207
所以我们要把40放在这里

150
00:05:13,207 --> 00:05:16,154
百位进1

151
00:05:16,154 --> 00:05:19,440
但是100不知道放在哪

152
00:05:19,450 --> 00:05:22,001
可以写在这

153
00:05:22,001 --> 00:05:24,860
可以--

154
00:05:24,870 --> 00:05:35,155
也可以写在这

155
00:05:35,155 --> 00:05:37,774
写在这里

156
00:05:37,774 --> 00:05:39,255
很多地方可以写

157
00:05:39,255 --> 00:05:40,510
这个100

158
00:05:40,510 --> 00:05:41,800
但是最重要的一点不要忘记

159
00:05:41,800 --> 00:05:42,820
这个一百是在百位上

160
00:05:42,820 --> 00:05:47,130
分隔线我刚没画

161
00:05:47,140 --> 00:05:49,950
这样再写一个100

162
00:05:49,950 --> 00:05:52,840
得到是100+40+4

163
00:05:52,850 --> 00:05:54,820
即144

164
00:05:54,820 --> 00:05:56,000
希望大家能听懂

165
00:05:56,010 --> 00:05:59,560
再来多做几个题

166
00:05:59,560 --> 00:06:02,100
多看例题是很重要的

167
00:06:02,110 --> 00:06:04,184
计算55×8

168
00:06:04,184 --> 00:06:07,170
55×8

169
00:06:07,180 --> 00:06:08,183
差不多的例题

170
00:06:08,183 --> 00:06:11,910
要用8开始乘

171
00:06:11,920 --> 00:06:14,714
8×5

172
00:06:14,714 --> 00:06:18,830
我先写下来

173
00:06:18,830 --> 00:06:27,260
8×5=40

174
00:06:27,270 --> 00:06:28,950
把0写在这

175
00:06:28,950 --> 00:06:31,240
进位4

176
00:06:31,250 --> 00:06:33,050
然后又是8×5

177
00:06:33,050 --> 00:06:36,550
还是40

178
00:06:36,550 --> 00:06:40,470
不过再加上进位4 是44

179
00:06:40,470 --> 00:06:43,590
代表的是440

180
00:06:43,600 --> 00:06:46,540
你可以像我上个题一样

181
00:06:46,550 --> 00:06:49,750
把55拆成50+5再分别乘以8

182
00:06:49,750 --> 00:06:52,045
不过做的题多了

183
00:06:52,045 --> 00:06:53,480
应该大家会习惯这么运算的

184
00:06:53,490 --> 00:06:55,580
再做一个--

185
00:06:55,580 --> 00:06:57,960
换个颜色

186
00:06:57,970 --> 00:07:01,790
浅红色

187
00:07:01,800 --> 00:07:02,562
用78乘以--

188
00:07:02,562 --> 00:07:06,175
乘以7

189
00:07:06,175 --> 00:07:08,190
8×7

190
00:07:08,190 --> 00:07:09,680
8×7=56

191
00:07:09,680 --> 00:07:13,810
写下来--这又是一个新题

192
00:07:13,820 --> 00:07:16,804
8×7=56

193
00:07:16,804 --> 00:07:25,865
把6写在下边 进位5写在上边

194
00:07:25,865 --> 00:07:27,600
7×7=49

195
00:07:27,600 --> 00:07:31,390
7乘以7得49

196
00:07:31,390 --> 00:07:33,070
还要加上边的5

197
00:07:33,080 --> 00:07:35,287
再加上5

198
00:07:35,287 --> 00:07:36,847
49+5=？

199
00:07:36,847 --> 00:07:38,360
是54

200
00:07:38,370 --> 00:07:40,330
7×7=49

201
00:07:40,330 --> 00:07:42,950
49+5=54

202
00:07:42,950 --> 00:07:46,240
得546

203
00:07:46,250 --> 00:07:47,535
不久前你可能还觉得

204
00:07:47,535 --> 00:07:49,120
光用1-12的乘法表

205
00:07:49,120 --> 00:07:50,150
肯定求不出78的乘法表

206
00:07:50,160 --> 00:07:51,940
但大家可以看到过程其实非常简单

207
00:07:51,940 --> 00:07:54,510
再多做几个

208
00:07:54,520 --> 00:07:57,760
一直算到不能再算为止

209
00:07:57,760 --> 00:07:59,135
算到精疲力竭为止

210
00:07:59,135 --> 00:08:04,147
89×3

211
00:08:04,147 --> 00:08:06,689
89×3=？

212
00:08:06,689 --> 00:08:09,177
3×9=27

213
00:08:09,177 --> 00:08:20,374
7写在个位

214
00:08:20,374 --> 00:08:23,178
向十位进位2

215
00:08:23,178 --> 00:08:24,712
因为27=20+7

216
00:08:24,712 --> 00:08:27,992
两个10就是20

217
00:08:27,992 --> 00:08:29,562
加7是27

218
00:08:29,562 --> 00:08:32,480
然后3×8=24

219
00:08:32,480 --> 00:08:34,446
3×8=24

220
00:08:34,446 --> 00:08:35,870
上边还有一个2的进位

221
00:08:35,870 --> 00:08:37,870
还要再加2

222
00:08:37,880 --> 00:08:39,430
得26

223
00:08:39,440 --> 00:08:41,670
3×8=24

224
00:08:41,670 --> 00:08:45,080
24+2=26

225
00:08:45,090 --> 00:08:48,640
结果是267

226
00:08:48,640 --> 00:08:49,820
再做一个

227
00:08:49,830 --> 00:08:52,184
不过我要加难度了

228
00:08:52,184 --> 00:08:54,397
在你觉得

229
00:08:54,397 --> 00:08:56,742
这些都会做的时候

230
00:08:56,742 --> 00:08:58,530
我再出一个能难到你的！

231
00:08:58,530 --> 00:09:02,178
239×6

232
00:09:02,178 --> 00:09:03,682
本来是要做

233
00:09:03,682 --> 00:09:10,160
两位数乘一位数的视频的

234
00:09:10,160 --> 00:09:10,902
不过这题也是告诉大家

235
00:09:10,902 --> 00:09:13,788
不管是几位数去乘一个一位数

236
00:09:13,788 --> 00:09:14,645
你都是可以做的

237
00:09:14,645 --> 00:09:18,360
步骤大同小异

238
00:09:18,360 --> 00:09:19,973
大家可以猜一猜这个要怎么做

239
00:09:19,973 --> 00:09:21,400
6×9=？

240
00:09:21,400 --> 00:09:24,490
在这里写

241
00:09:24,500 --> 00:09:27,830
6×9

242
00:09:27,830 --> 00:09:32,200
这个之前算过了

243
00:09:32,200 --> 00:09:34,140
54

244
00:09:34,140 --> 00:09:36,390
把4写在这

245
00:09:36,400 --> 00:09:38,790
5放在十位

246
00:09:38,800 --> 00:09:41,490
因为这个54中的5就是5个10

247
00:09:41,490 --> 00:09:43,800
好

248
00:09:43,800 --> 00:09:46,380
然后是6×3

249
00:09:46,380 --> 00:09:49,228
6×3

250
00:09:49,228 --> 00:09:52,610
得18

251
00:09:52,610 --> 00:09:57,350
上边还有一个5

252
00:09:57,350 --> 00:10:01,140
还要加5

253
00:10:01,140 --> 00:10:02,290
18+5=？

254
00:10:02,300 --> 00:10:03,490
6×3=18 18+5=23

255
00:10:03,500 --> 00:10:06,710
澄清一点

256
00:10:06,710 --> 00:10:08,320
并不是用6×3+5

257
00:10:08,320 --> 00:10:09,770
你看

258
00:10:09,770 --> 00:10:12,251
在这个问题里

259
00:10:12,251 --> 00:10:15,025
3其实是30

260
00:10:15,025 --> 00:10:17,365
只不过写的是3

261
00:10:17,370 --> 00:10:18,620
但这其实是6×30+50

262
00:10:18,620 --> 00:10:20,120
因为39的3是3个10 或者是30

263
00:10:20,130 --> 00:10:21,830
那么

264
00:10:21,840 --> 00:10:23,500
虽然这里说6×3=18

265
00:10:23,500 --> 00:10:25,497
18+5=23

266
00:10:25,497 --> 00:10:26,740
实际得到的其实是230

267
00:10:26,740 --> 00:10:29,090
把3放在十位

268
00:10:29,090 --> 00:10:35,210
我换个颜色来写

269
00:10:35,210 --> 00:10:38,197
用个跟上边不一样的

270
00:10:38,197 --> 00:10:40,980
结果是23

271
00:10:40,980 --> 00:10:42,869
把3放在十位

272
00:10:42,869 --> 00:10:46,615
向百位进2 写上边

273
00:10:46,615 --> 00:10:53,058
差不多就做完了 再乘最后一次

274
00:10:53,058 --> 00:10:53,814
6×2

275
00:10:53,814 --> 00:10:56,210
这个很简单

276
00:10:56,220 --> 00:10:58,320
得12

277
00:10:58,320 --> 00:10:59,900
但是上边还有进位2

278
00:10:59,900 --> 00:11:01,260
所以还要再加2

279
00:11:01,260 --> 00:11:03,380
+2

280
00:11:03,390 --> 00:11:06,202
等于什么呢？

281
00:11:06,202 --> 00:11:08,130
12+2=14

282
00:11:08,145 --> 00:11:10,125
写4

283
00:11:10,130 --> 00:11:13,960
6×2=12

284
00:11:13,970 --> 00:11:18,675
12+2=14

285
00:11:18,675 --> 00:11:20,841
把4写在下边

286
00:11:20,841 --> 00:11:23,254
如果这里还有更高位的话就写在上边

287
00:11:23,270 --> 00:11:27,140
但是没有了

288
00:11:27,140 --> 00:11:34,370
所以直接写在这就可以了

289
00:11:34,370 --> 00:11:36,348
239×6

290
00:11:36,348 --> 00:11:38,961
=1434

291
00:11:38,961 --> 00:11:40,707
再做一个

292
00:11:40,710 --> 00:11:44,158
需要清一些空间出来

293
00:11:44,158 --> 00:11:47,350
既然已经增加难度了

294
00:11:47,360 --> 00:11:50,460
下面来做一个四位数的吧

295
00:11:50,460 --> 00:11:52,032
7362×--

296
00:11:52,032 --> 00:11:54,552
难点的--9

297
00:11:54,552 --> 00:11:56,872
9×2=？

298
00:11:56,872 --> 00:12:00,494
我就不再写在旁边了

299
00:12:00,494 --> 00:12:05,024
大家应该已经明白这个套路了

300
00:12:05,024 --> 00:12:07,200
9×2=？