[Help-bash] Help With School Assignment, Learning Bash Scripts

[nick]

I am trying to feature out the below question and can't seem able to.
Cheers Nick 
The best approach is to check each positional parameter within the loop,
before the addition.

You will use an "echo" to display the value of the "number" variable,
and pipe the output into a "grep".  The "grep" should search for a single
character which is NOT a digit or a plus or minus sign.  A character class,
something like "[^0-9+-]" would be the easiest way to do this.

If the "grep" is successful, then the message should be displayed and the
script terminated.

Continue to the next step to see how to start.