Creating a calculator script

Question

I am trying to make a calculator with a bash script. The user enters a number, chooses whether they wish to add, subtract, multiply or divide. Then the user enters a second

Answer 1

This calculates uses up to 4 decimals (if needed), works without quotation marks.

calc () 
{ 
    echo "scale=4;$*" | bc -l
}

Only downside is, you have to escape *, else the shell will use it for file expansion.

Usage:

calc 1 + 2
calc 3 - 4
calc 44 \* 88
calc 77 / 234

This should do for most cases where you need a calculator fast.