Math Expressions

Math expressions let you compute values inline on either side of a comparison, without needing to pre-compute fields in your data.

Syntax

Math expressions support full nested arithmetic:

<expression> <comparison> <expression>

An expression can contain:

• properties
• literal numbers
• +, -, *, /
• natural-language aliases
• parentheses

Operator	Accepted forms
addition	+, plus, added to
subtraction	-, minus, subtracted by
multiplication	*, times, multiplied by
division	/, divided by

Precedence

The engine applies normal arithmetic precedence:

1. parentheses
2. multiplication and division
3. addition and subtraction

This means multiplication happens before addition:

__subtotal__ of **Order** + __tax__ of **Order** * 2 is greater than 100

Use parentheses when you want a different grouping:

(__subtotal__ of **Order** + __tax__ of **Order**) * 2 is greater than 100

Addition

__subtotal__ of **Order** + __tax__ of **Order** is greater than 100

Aliases also work:

__subtotal__ of **Order** plus __tax__ of **Order** is greater than 100

Interactive Example

Reset

Policy Rule

A **Order** requires signature
if __subtotal__ of **Order** + __tax__ of **Order** is greater than 100.

A **Order** requires signature if __subtotal__ of **Order** + __tax__ of **Order** is greater than 100.

Test Data (JSON)

{
  "Order": { "subtotal": 90, "tax": 15 }
}

{ "Order": { "subtotal": 90, "tax": 15 } }

Run

Mix a property with a literal:

Interactive Example

Reset

Policy Rule

A **Product** is premium
if __base_price__ of **Product** + 20 is greater than 50.

A **Product** is premium if __base_price__ of **Product** + 20 is greater than 50.

Test Data (JSON)

{
  "Product": { "base_price": 35 }
}

{ "Product": { "base_price": 35 } }

Run

Subtraction

__balance__ of **Account** - __pending__ of **Account** is at least 0

Interactive Example

Reset

Policy Rule

A **Account** has sufficient funds
if __balance__ of **Account** - __reserved__ of **Account** is at least 100.

A **Account** has sufficient funds if __balance__ of **Account** - __reserved__ of **Account** is at least 100.

Test Data (JSON)

{
  "Account": { "balance": 500, "reserved": 350 }
}

{ "Account": { "balance": 500, "reserved": 350 } }

Run

Multiplication

__quantity__ of **Order** * __unit_price__ of **Order** is greater than 1000

Interactive Example

Reset

Policy Rule

A **Order** qualifies for wholesale pricing
if __quantity__ of **Order** * __unit_price__ of **Order** is at least 500.

A **Order** qualifies for wholesale pricing if __quantity__ of **Order** * __unit_price__ of **Order** is at least 500.

Test Data (JSON)

{
  "Order": { "quantity": 10, "unit_price": 60 }
}

{ "Order": { "quantity": 10, "unit_price": 60 } }

Run

Division

__revenue__ of **Store** / __expenses__ of **Store** is greater than 1.5

Interactive Example

Reset

Policy Rule

A **Store** is profitable
if __revenue__ of **Store** / __expenses__ of **Store** is greater than 1.

A **Store** is profitable if __revenue__ of **Store** / __expenses__ of **Store** is greater than 1.

Test Data (JSON)

{
  "Store": { "revenue": 12000, "expenses": 8000 }
}

{ "Store": { "revenue": 12000, "expenses": 8000 } }

Run

Nested Expressions

You can nest expressions and put arithmetic on both sides of the comparison:

(__used__ of **Quota** + __buffer__ of **Quota**) * 2 is less than __limit__ of **Quota** * 3 - 1

Interactive Example

Reset

Policy Rule

A **Quota** is safe
if (__used__ of **Quota** + __buffer__ of **Quota**) * 2 is less than __limit__ of **Quota** * 3 - 1.

A **Quota** is safe if (__used__ of **Quota** + __buffer__ of **Quota**) * 2 is less than __limit__ of **Quota** * 3 - 1.

Test Data (JSON)

{
  "Quota": { "used": 10, "buffer": 4, "limit": 7 }
}

{ "Quota": { "used": 10, "buffer": 4, "limit": 7 } }

Run

Combining with Other Conditions

Math expressions can be combined with and and or like any other condition:

Interactive Example

Reset

Policy Rule

A **Applicant** is approved
if __income__ of **Applicant** - __debt__ of **Applicant** is at least 30000
and __age__ of **Applicant** is at least 18.

A **Applicant** is approved if __income__ of **Applicant** - __debt__ of **Applicant** is at least 30000 and __age__ of **Applicant** is at least 18.

Test Data (JSON)

{
  "Applicant": { "income": 70000, "debt": 25000, "age": 30 }
}

{ "Applicant": { "income": 70000, "debt": 25000, "age": 30 } }

Run

Errors And Traces

Every arithmetic step must resolve to numbers.

• Non-numeric operands return a type error that includes the failing expression.
• Division by zero returns an evaluation error that includes the full expression.
• Execution traces expose the evaluated left-hand expression path and the final right-hand value, so the UI can explain what was compared.

Example errors:

Arithmetic expression $.Applicant.status resolved to string, but numeric operands are required
Division by zero in arithmetic expression ($.Student.total / ($.Student.count - $.Student.count))

Summary

Capability	Supported
literal numbers	yes
property references	yes
math on the left side	yes
math on the right side	yes
nested expressions	yes
parentheses	yes
precedence (*// before +/-)	yes

Operator	Accepted forms	Example
addition	+, plus, added to	__subtotal__ of **Order** plus __tax__ of **Order** is greater than 50
subtraction	-, minus, subtracted by	__balance__ of **Account** minus __reserved__ of **Account** is at least 0
multiplication	*, times, multiplied by	__qty__ of **Order** times __price__ of **Order** is greater than 100
division	/, divided by	__revenue__ of **Store** divided by __costs__ of **Store** is greater than 1