WEBVTT

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1+4=5 最高位是1 希望大家能看到

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1+9=10

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10+4=14 进1

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12+1=13

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150462

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18+2=20 进2

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4×2=8 8+1

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4×3=12

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4×4--

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4×4=16 进1

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4就乘完了

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6×2=12 12+2=14

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6×3=18

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6×4=24 进2

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下面是6 因为是600

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个位是2 十位是6 百位7+3=10

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代表的是40 在这写个0

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做等级四的习题了！

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先把上边的进位都划掉

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因为4在十位上

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大家现在可以

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希望没有写到屏幕以外吧

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应该是没问题

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得9

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我把自己弄糊涂了

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我经常忘了划掉这些

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所以填两个0

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把之前的进位都划掉

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接下来乘4 或者说40

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然后就像乘6一样来运算

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现在都加起来

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说40也行 看你怎么看了

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进1

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那么我的答案是

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下面来做等级四的乘法运算

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来看一些例题

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用235乘以--

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用两种不同颜色来表示

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换颜色的时候大家可能要稍微等一下

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235乘以47

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做等级四的题目

00:00:26.960 --> 00:00:31.060
就跟做等级三的方法是一样的

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一开始也是用这个7

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乘以235

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7×5=35 进3

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7×3=21

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加上之前的进位3 得24 进2

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7×2=14

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再加上进位2

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得16

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7就乘完了

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然后要乘这个4

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但4是在十位上

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所以要在下边加一个0

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大家可以这么看

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乘235的

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不是4 而是40

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所以要填一个0

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但是在写了0以后

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就可以看成是乘4来运算了

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4×5=20 进2

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把上一步的进位划掉

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4×3=12

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加上进上来的2

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得14 进1

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4×2=8

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加上进位1

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得9

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现在把两个乘积加起来

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5+0=5

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4+0=4

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6+4=10 进1

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1+1+9 得11

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所以结果是11045

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再做一道

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用873乘以--

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我是在临时凑数

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所以比较慢--

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873乘以--找个大数--

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9--个位十位我用不同的颜色写

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这样大家就能更好理解

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我说的是什么意思了

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乘以97

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刚用过7了

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就98吧

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就跟之前的步骤一样 先看个位

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也就是8

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8×873

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8×3=24

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进2

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8×7=56

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56+2=58

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进5

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8×8=64

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加上刚进的5

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就是69

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8就乘完了

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接下来乘9

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或者说

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是873乘以90

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但是乘以90就是

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乘以9--

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后边再加个0

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所以在这写个0

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然后9×3=27 进2

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忘了要先划掉这些进位了

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把之前写的都划掉

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9×3=27

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进2

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9×7=63

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加上进位2 是65

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进6

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9×8=72

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加上进位6

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是78

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然后再做加法

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个位是4 8+7=15 进1

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1+9+5=15 进1

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1+6+8还是15 进1

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1+7=8

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手边又没有计算器--

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如果我没算错的话--

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如果没有粗心计算错误

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那么答案是85554

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再做一道

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这道题能清楚阐释我要说的内容

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下一道题

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差不多是等级五的内容

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因为我要写的是

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两个三位数相乘

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但其实道理是一样的

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希望大家能够发现运算的规律

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那么 234乘以--

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现在要用三种颜色来写了

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643

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首先来算个位的3

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8×234

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3×4=12 进1

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3×3=9 9+1

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得10 进1

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3×2=6 6+1

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得7

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个位就做完了

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我觉得哪里做错了 来看一下

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3×4=12--