# Number Variable Rules

{% hint style="info" %}
Use Number Variables to track the number of times a viewer performs an action or to store a score or any other number.
{% endhint %}

Example Experience where you can track the number of times the viewer enters a zone:

(Try walking into the blue zone and see the count increment)

{% embed url="<https://demo.gmetri.com/variables_demo>" %}
Example Experience to track how many times the viewer enters the blue zone
{% endembed %}

These are the rules that were used in the above experience:

<figure><img src="https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-Mgll1jjQMRTVj7p6n7g%2Fuploads%2Fg45VURelNSWyQ3FY2EuO%2Fimage.png?alt=media&#x26;token=ad42072b-3be8-4fbb-afd9-351c27f99af1" alt=""><figcaption><p>Rules - Number Variables</p></figcaption></figure>

## Number: When Rules

<figure><img src="https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-Mgll1jjQMRTVj7p6n7g%2Fuploads%2FKnr7P8AjKSsNUtQH32q8%2Fimage.png?alt=media&#x26;token=8eb15d8b-cb09-4659-b874-80ae624a0c22" alt=""><figcaption><p>Number: When Rules</p></figcaption></figure>

1. **changes**:  Gets triggered if the number variable undergoes a change.
2. **is between**: Gets triggered if the number variable is within a certain range.
3. **is =**, **is >**, **is > OR =**, i**s <**, i**s < OR =**: Comparison operators that trigger when the given condition becomes true.
4. **is in the list / is not in the list**: A certain action can be triggered if the number value exists in a given comma-separated list.

<figure><img src="https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-Mgll1jjQMRTVj7p6n7g%2Fuploads%2Ffyk4McFYpyH77ZTVyrTk%2Fimage.png?alt=media&#x26;token=8124693b-a99c-4701-bab4-aba51633ca68" alt=""><figcaption><p>Is In List Rule</p></figcaption></figure>

## Number: Then Rules

1. **reset to default value** - This will set the variable back to its default value.
2. **set to number** - This action allows you to set the variable to a particular number.
3. **set to formula** - This action enables you to use a formula that generates results to set the value of the variable.
4. **add number** - This action allows you to add a particular number to the variable.
5. **capture data** - This action copies the value from the "When" side of the rule. Check [String Substitution](/metaverse/build/variables/string-substitution.md#capturing-user-input).
6. **add captured value** - This action adds the captured value to the variable (instead of replacing it with the value).

<figure><img src="https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-Mgll1jjQMRTVj7p6n7g%2Fuploads%2FuxIMAk6cS0rkBdMvF2yL%2Fimage.png?alt=media&#x26;token=4515483d-2052-45bd-99cd-444999e86eae" alt=""><figcaption><p>Number: Then Rules</p></figcaption></figure>

## Number: Formulas

You can do a lot with the Then option *set to formula* for Numbers.

### Mathematical Expressions

You can write any formula in the "Set to formula" value to get it evaluated by GMetri.

{% hint style="info" %}
Formula expressions also support [Variable Substitution](#using-variables-through-text-substitution).
{% endhint %}

The following types of expressions are supported:

|                    Input                   |       Result      | Explanation                                                      |
| :----------------------------------------: | :---------------: | ---------------------------------------------------------------- |
|                  **2+3-1**                 |         4         | Addition and Subtraction operator                                |
|                 **2\*5/10**                |         1         | Multiplication and Division operator                             |
|         **tan45** *or* **tan(45)**         |         1         | Trigonometric Function (tan in Degree mode)                      |
|         **tan45** *or* **tan(45)**         | 1.619775190543862 | Trigonometric Function (tan in Radian mode)                      |
|      **Pi1,15,n** *or* **Pi(1,15,n)**      |   1307674368000   | Product of Sequence                                              |
|   **Sigma1,15,n** *or* **Sigma(1,15,n)**   |        120        | Sum of Sequence (also called summation)                          |
|                   **2^3**                  |         8         | Exponent (note this operator is left associative like MS Office) |
|                   **5P3**                  |         60        | Permutaion Method to calculate all the permutaions               |
| **sincostan90** *or* **sin(cos(tan(90)))** | 0.017261434031253 | Multiple functions with or without parenthesis (both works)      |

### Random Number

Set the "Set to formula" value to `random_<from>_<to>` to generate a random number.  Replace "\<from>" and "\<to>" with numbers, no spaces in between - like `random_0_5`. For example, if you want to generate a random number between 3 and 8, you should set this to `random_3_8`.

### Current Time

Set the "Set to formula" value to `current_time` to save the current epoch time (in ms) in a number variable.

{% embed url="<https://demo.gmetri.com/randomno_demo>" %}
Number: formulas
{% endembed %}

Rules used in the above experience:

<figure><img src="https://files.gitbook.com/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-Mgll1jjQMRTVj7p6n7g%2Fuploads%2FlifI1RyFpwLlziYBq4QY%2Fimage.png?alt=media&#x26;token=be0e0f4b-c22f-4fd8-a293-99ba24aa66ed" alt=""><figcaption><p>Formula based rules</p></figcaption></figure>


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