# Calculations

Inline code can do arithmetic. Put an expression in backticks and end it with `=`, and Thymer shows the result right after it:

```text
`12 * 3 =`          shows 36
`(4 + 5) / 2 =`     shows 4.50
```

Name a value and use it anywhere on the page:

```text
`hours = 6`
`rate = 80`
`total = hours * rate`     shows 480
`total * 1.21 =`           shows 580.80
```

## What an expression can contain

- Numbers: `12`, `12.5`, `.5`, and negative numbers like `-3`.
- Names: letters, digits and underscores, starting with a letter or an underscore, such as `rate` or `q3_target`.
- The operators `+`, `-`, `*` and `/`, with the usual precedence: multiplication and division first.
- Parentheses to group.

Whole numbers show as they are; anything else shows with two decimals.

## How values are shared

A page is one calculation space: every name defined in inline code on the page is available to every expression on it, in any order. Change `hours` at the top and `total` further down updates. A transcluded section or a live query block keeps its own space.

A plain `` `hours = 6` `` shows no result, only defines the name. `` `total = hours * rate` `` defines a name and shows its value. An expression that ends with `=` only shows a value.

## When nothing shows

If an expression refers to a name that is not defined, divides by zero, or two names depend on each other, the result is `NaN`. If a page has no definitions at all, Thymer shows nothing for an undefined name, so a stray `` `x + y =` `` in ordinary notes stays quiet. A typo like `5 + * 3 =` shows nothing either.

Calculations work in the text of a page. To compute a property from a page's other properties, use a [Formula](../collections/formulas.md).