# Working with numbers

You can use math expressions to insert values into fields or set values of a number custom field anywhere where custom fields can be edited (create, edit & transition actions). Details of operators, functions and constants are in the math reference section.

In a number custom field you can use an expression to set a value:

To use a math expression in another field, insert the value using:

## Referencing number fields

To perform calculations with number custom fields in Jira, you can simply reference the field as a smart value in your calculation:

Or, if you wanted to add two custom fields you could use: