# Number Variable Rules

Use Number Variables to track the number of times a viewer performs an action or to store a score or any other number.
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)
Example Experience to track how many times the viewer enters the blue zone
These are the rules that were used in the above experience: Rules - Number Variables

## Number: When Rules Number: When Rules
1. 1.
changes: Gets triggered if the number variable undergoes a change.
2. 2.
is between: Gets triggered if the number variable is within a certain range.
3. 3.
is =, is >, is > OR =, is <, is < OR =: Comparison operators that trigger when the given condition becomes true.
4. 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. Is In List Rule

## Number: Then Rules

1. 1.
reset to default value - This will set the variable back to its default value.
2. 2.
set to number - This action allows you to set the variable to a particular number.
3. 3.
set to formula - This action enables you to use a formula that generates results to set the value of the variable.
4. 4.
add number - This action allows you to add a particular number to the variable.
5. 5.
capture data - This action copies the value from the "When" side of the rule. Check .
6. 6.
add captured value - This action adds the captured value to the variable (instead of replacing it with the value). Number: Then Rules

## 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.
Formula expressions also support Variable Substitution.
The following types of expressions are supported:
Input
Result
Explanation
2+3-1
4
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 save the current epoch time (in ms) in a number variable. 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.
Number: formulas
Rules used in the above experience: Formula based rules