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# Math Function formula syntax, functions and messages

> Reference for Mammoth Math Function formulas: column and operator syntax, SUM, AVG, INT and ABS, Number parameters, ID warnings and every validation message.
>
> Applies to: Where: View › Describe your transformation › Date, Numeric & Text › Math Function › Formula

In **Formula** mode, a Math Function formula combines Number columns, numbers, operators, brackets, built-in functions and Number parameters. Mammoth checks it as you type and shows "Looks good" or the problem. For the steps to add the column, see [Calculate with formulas](https://mammoth.io/docs/learn/clean-and-shape/formulas/).

## Formula syntax and built-in functions

| Part | How to write it |
| --- | --- |
| Column | The column name in double quotes, such as `"unit_price"`. Only Number columns are allowed. |
| Number | A plain number, such as `12` or `0.5` |
| Operators | `+`, `-`, `*` and `/`. Multiplication and division run before addition and subtraction. |
| Brackets | `(` and `)` to group parts of the formula |
| Parameter | A Number parameter in curly braces, such as `{Max_Units}` |

A formula can start with `-` or `+` but not with `*` or `/`. An empty cell in a column counts as 0. Dividing by 0 leaves the result cell empty.

| Function | Takes | Returns |
| --- | --- | --- |
| `SUM("Column")` | One Number column | The column total |
| `AVG("Column")` | One Number column | The column average |
| `MIN("Column")` | One Number column | The smallest value in the column |
| `MAX("Column")` | One Number column | The largest value in the column |
| `STDDEV("Column")` | One Number column | The column's standard deviation |
| `COUNT()` | Nothing | The number of rows |
| `INT(expression)` | Any formula | The whole-number part. It drops the decimals rather than rounding, so `INT(7.9)` is 7 and `INT(-7.9)` is -7. |
| `ABS(expression)` | Any formula | The value without its sign, so `ABS(-4)` is 4 |

`SUM`, `AVG`, `MIN`, `MAX`, `STDDEV` and `COUNT` look at the whole column, not the current row, so every row gets the same value. If the step has a condition built in **Builder**, they cover only the matching rows. `INT` and `ABS` take a full formula, so they can wrap other functions: `INT(SUM("units") / COUNT())`.

## Use a parameter in a formula

Click **Insert Parameter** above the formula, or pick the parameter from the autocomplete list. Only Number parameters can be used in a formula. Each run uses the parameter's current value. When the value changes, the pipeline is marked stale until you rerun it. See [Parameters and snippets](https://mammoth.io/docs/learn/organise/parameters-and-snippets/).

## Warnings about IDs and money in a formula

In Formula mode, Mammoth adds a note when a formula does arithmetic on a column marked as an ID ("IDs are labels, not amounts, so doing arithmetic on them isn't meaningful.") or mixes an amount of money with a percentage ("This formula mixes an amount of money with a percentage. Check that the result is what you mean."). The notes never block the step. See [Column types, IDs, currency and percentages](https://mammoth.io/docs/learn/clean-and-shape/column-types/).

## Troubleshooting formula messages

| Message | What to fix |
| --- | --- |
| "Empty expression" | Type a formula. |
| "Expression can not begin with * or /" | Start with a column, number, function, bracket or minus sign. |
| "Expression can not end with any of +, -, *, /" | Finish the formula after the last operator. |
| "Operators +, -, *, / can not be followed by other operators" | Remove the doubled operator. |
| "Expected an operator +, -, *, / before ..." | Add an operator between two values. |
| "Syntax error: unmatched brackets" | Every `(` needs a matching `)`. |
| "Only numeric columns allowed" | Use a Number column, or convert the column first with [Convert Column Type](https://mammoth.io/docs/learn/clean-and-shape/convert-column-type/). |
| "Column ... is missing" | The column was renamed or removed earlier in the pipeline. |
| "Function ... takes no arguments" | Write `COUNT()` with nothing inside. |
| "Function ... takes exactly 1 argument" | Give `SUM`, `AVG`, `MIN`, `MAX` or `STDDEV` one column. |
| "Invalid arguments for ..." | The function needs a column in double quotes. |
| "Invalid: ..." | The text isn't a column, number, operator, function or parameter. Check the spelling and quotes. |
| "Parameter ... not found" | No parameter has that name. |
| "Only numeric parameters allowed, ... is not one" | Use a Number parameter. |

In the formula's column list, a column can be marked "(column missing)" or "(not a numeric column)".

Other problems:

| Symptom | Cause | Fix |
| --- | --- | --- |
| Every row shows the same value | `SUM`, `AVG`, `MIN`, `MAX`, `STDDEV` or `COUNT` looks at the whole column | Combine it with a column, for example `"revenue" / SUM("revenue")` |
| Result cells are empty | Division by 0, or rows outside the step's condition in a new column | Check divisors and the condition |

## Related

- [Calculate with formulas](https://mammoth.io/docs/learn/clean-and-shape/formulas/): create the column in SQL or Formula mode.
- [Convert text to dates and numbers](https://mammoth.io/docs/learn/clean-and-shape/convert-column-type/): make a column numeric first.
- [Column types, IDs, currency and percentages](https://mammoth.io/docs/learn/clean-and-shape/column-types/): why IDs and money trigger notes.

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Source: https://mammoth.io/docs/learn/clean-and-shape/formula-syntax.md · Updated: 2026-11-08