35 lines
1.2 KiB
Markdown
35 lines
1.2 KiB
Markdown
# 乘法
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> 乘法（英语：Multiplication），加法的连续运算，同一数的若干次连加，其运算结果称为积（英语：Product）。
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$$ \sum_{k=1}^{n}{m} = \underbrace{m + m + m + \cdots + m}_{n} = m \times n $$
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## 表示法
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- $ m \times n $
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- $ m \cdot n $
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- $ m * n $
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- $ mn $ (代数中，乘号经常省略掉)
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## 性质
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- 交换律 $a \times b = b \times a$
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- 结合律 $ (a \times b) \times c = a \times (b \times c)$
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- 分配律 $a \times (b+c)= a\times b + a\times c$
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## 乘法口诀表
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| X | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
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| 1 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
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| 2 | 2 | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18 |
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| 3 | 3 | 6 | 9 | 12 | 15 | 18 | 21 | 24 | 27 |
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| 4 | 4 | 8 | 12 | 16 | 20 | 24 | 28 | 32 | 36 |
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| 5 | 5 | 10 | 15 | 20 | 25 | 30 | 35 | 40 | 45 |
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| 6 | 6 | 12 | 18 | 24 | 30 | 36 | 42 | 48 | 54 |
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| 7 | 7 | 14 | 21 | 28 | 35 | 42 | 49 | 56 | 63 |
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| 8 | 8 | 16 | 24 | 32 | 40 | 48 | 56 | 64 | 72 |
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| 9 | 9 | 18 | 27 | 36 | 45 | 54 | 63 | 72 | 81 |
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