Linux Script File

[SteveAH10]

I am attempting to learn scripting and I have started a script in vi to calculate numbers. I want it to add, subtract, divide, and multiply integers.

I want to enter " calck plus 1 2 3 4", where plus is the operation (sub, divide, and Mult will be used as well), and the numbers are to be acted upon.
I have written a test script which follows

:

total=0

for plus in $1

do
if [ $1 = plus ]
then
total=`expr$total+$*`
echo $total
fi
done

But I know my expression is not right! Can anyone give me an idea of what I am doing wrong. I would appreciate any help I can receive.
( I was thinking I might be able to use Case instead of if as well)

Steve