A **numerical operation** can be described as an action or process used to solved a numerical problem.

**Adding and Subtracting Signed Numbers **

If you have two numbers *x* and *y*, the following rules apply when these numbers are being **added** or **subtracted**.

**Rule of Signs for Addition:**(*x*–*y*) is the same as*x*+ (–*y*) or*x*– (+y) because a negative beside a positive (*or vice versa*) always make a negative.**Rule of Signs for Subtraction:***x*+*y*is the same as*x*– (–*y*) because two negatives side-by-side make a positive.

Here are a few examples:

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**For #1**, the answer is clearly 9. But you could also have gotten 9 if you had: 7 – (–2) because of the *rule of signs for subtraction*.

**For #2**, the answer is 5. But you could also have gotten 5 if you had: 9 + (–4) or 9 – (+4) because of the *rule of signs for addition*.

**For #3**, the answer is –2.

A summary of these symbols is shown below:

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More examples: null

**#1:** 14

**#2:** –2

**#3:** 18

**Multiplying and Dividing Signed Numbers **

**Rules of Signs for Multiplication:**- (+x)(+y) = (–x)(–y) = +xy
- (+x)(–y) = (–x)(+y) = –xy

- It’s also important to note that the same rules apply for division too.

Multiplication of two or more factors can be symbolized in 3 main ways:

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For division:

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Here are a few examples:

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