# Math --- Enable the Math module under [Settings](options-general.php?page=ccs_reference&tab=settings). --- Use `[calc]` to perform safe, spreadsheet-like calculations. ~~~ Total: [calc][field price] * [field amount][/calc] ~~~ Numbers can be assigned to variables. ~~~ [calc]total = [field price] * [field amount][/calc] ~~~ When you assign a variable, it displays nothing. These variables are shared with the `[get]` and `[set]` shortcodes described under [Advanced: Extras](options-general.php?page=ccs_reference&tab=extras#variables). --- To use a variable: ~~~ Total: [calc]total[/calc] Tax: [calc]total * 0.19[/calc] ~~~ The result can be formatted. ~~~ [format decimal=2][calc]total[/calc][/format] ~~~ For more information on the `[format]` shortcode, also see [Advanced: Extras](options-general.php?page=ccs_reference&tab=extras#format).