# Arithmetic expansion

# Arithmetic expansion#

If you want to perform a calculation and *use the resulting base 10 string for something* the syntax is `$((EXPRESSION))`

. This is called **arithmetic expansion** because Bash expands (replaces) the arithmetic expression with a string when running the command, and the inside of the parentheses is called a **numeric context** because the expression is treated as arithmetic rather than a string. An example, printing the result of x² – y², should make this clearer:

This page is a preview of *The newline Guide to Bash Scripting*

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