From 4da1ce578e1f89eb69fecede45841c0b93d27799 Mon Sep 17 00:00:00 2001
From: Zhao Xin <7176466@qq.com>
Date: Fri, 12 Aug 2022 15:51:06 +0800
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+# 乘法
+
+> 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）。
+
+$$\underbrace{m+m+m+\cdots+m}_{n} = m \times n = \sum_{k=1}^{n}{m}$$
+
+## 表示法
+
+- $ m \times n $
+- $ m \cdot n $
+- $ m * n $
+- $ mn $ (代数中，乘号经常省略掉)
+
+## 性质
+
+- 交换律 $a \times b = b \times a$
+- 结合律 $ (a \times  b) \times c = a \times (b \times c)$
+- 分配律 $a \times (b+c)= a\times b + a\times c$
+
+## 乘法口诀表
+
+| X   | 1   | 2   | 3   | 4   | 5   | 6   | 7   | 8   | 9   |
+| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
+| 1   | 1   | 2   | 3   | 4   | 5   | 6   | 7   | 8   | 9   |
+| 2   | 2   | 4   | 6   | 8   | 10  | 12  | 14  | 16  | 18  |
+| 3   | 3   | 6   | 9   | 12  | 15  | 18  | 21  | 24  | 27  |
+| 4   | 4   | 8   | 12  | 16  | 20  | 24  | 28  | 32  | 36  |
+| 5   | 5   | 10  | 15  | 20  | 25  | 30  | 35  | 40  | 45  |
+| 6   | 6   | 12  | 18  | 24  | 30  | 36  | 42  | 48  | 54  |
+| 7   | 7   | 14  | 21  | 28  | 35  | 42  | 49  | 56  | 63  |
+| 8   | 8   | 16  | 24  | 32  | 40  | 48  | 56  | 64  | 72  |
+| 9   | 9   | 18  | 27  | 36  | 45  | 54  | 63  | 72  | 81  |
+
+