# Arithmetic expansion

From LQWiki

Arithmetic expansion is the process by which shells replace an arithmetical expression by its result. In bash, the format for arithmetical expansion is $((expression)).

The order of operations within the expression is determined using normal arithmetical rules for operator precedence. So, for example, 5*(2+3) means "add 2 and 3 together first and then multiply the result by 5". (answer = 25).