bash arithmetic expressions with variables

Question

I am having troubles with the arithmetic expressions in a bash file (a unix file .sh).

I have the variable "total", which consists of a few numbers separated by spaces, and I want to calculate the sum of them (in the variable "dollar").

#!/bin/bash
..
dollar=0
for a in $total; do
  $dollar+=$a
done

I know I am missing something with the arithmetic brackets, but I couldn't get it to work with variables.

Answer 1

Wrap arithmetic operations within ((...)):

dollar=0
for a in $total; do
  ((dollar += a))
done