Simple command-line calculator

You can greatly reduce the amount of verbosity involved in using bc:

$ bc <<<"236-192"
44
$ bc <<<"1+1"
2

(assuming your shell supports that).

If you’d rather have that as a function:

$ c() { printf "%s\n" "$*" | bc }
$ c 1+1
2

Store the c definition in your favourite shell startup file if you want to make it always available.

Summary

There are several solutions listed (shell, awk, dc, perl, python, etc.).

A function may be defined with any option (gawk seems to be the most flexible to use)

c () { local in="$(echo " $*" | sed -e 's/\[/(/g' -e 's/\]/)/g')";
       gawk -M -v PREC=201 -M 'BEGIN {printf("%.60g\n",'"${in-0}"')}' < /dev/null
     }

And use it like:

$ c 236- 192
44

---

Shell

The simplest calc in CLI is the CLI (shell) itself (If IFS is default):

$ echo $(( 22 + 333 ))
355

Spaces could be omitted:

$ echo $((22*333))
7326

As it is part of POSIX almost all shells have it. And it includes most of C language math functionality (except that zsh has a different precedence, set C_PRECEDENCES to restore it to a compatible value):

$ echo $((22*333^2))
7324

And some shells have most of the C language math syntax (including comma):

$ echo $((a=22,b=333,c=a*b,c))
7326

But it is only integer math (and usually less than 2⁶³ in present day OSes) in some shells:

$ echo $((1234/3))
411

$ zsh -c 'echo $((2**63))'
-9223372036854775808

Some shells could do floating math:

$ ksh -c 'echo $((1234/3.0))'
411.333333333333333

$ ksh -c 'echo $((12345678901234567890123/3.0))'
4.11522630041152263e+21

Avoid zsh (zcalc has similar problems):

$ zsh -c 'echo $((12345678901234567890123 + 1))'
zsh:1: number truncated after 22 digits: 12345678901234567890123 + 1
-1363962815083169259

I recommend you to avoid expr, it needs weird escapes sometimes:

$ expr 22 \* 333
7326

bc

At the next level is (also POSIX)bc (cousin of RPN dc)

$ echo '22*333' | bc
7326

$ echo '22 333 * p' | dc
7326

The dc was (historically) used to implement bc and got excluded from POSIX in 2017.

Shorter if your shell supports it:

$ bc <<<'22*333'
7326

Or even:

$ <<<'22*333' bc
7326

Both are arbitrary precision calculators with some internal math functions:

$ bc <<<2^200
1606938044258990275541962092341162602522202993782792835301376

$ echo 's(3.1415/2)' | bc -l        # sine function
.99999999892691403749

awk

After those really basic calc tools, you need to go up to other languages

$ awk "BEGIN {print (22*33)/7}"
103.714

$ perl -E "say 22*33/7"
103.714285714286

$ python3 -c "print(22*33/7)"
103.71428571428571

$ php -r 'echo 22*33/7,"\n";'
103.71428571429

function

You may define a function of any of the above options:

c () 
{ 
    local in="$(echo " $*" | sed -e 's/\[/(/g' -e 's/\]/)/g')";
    gawk -M -v PREC=201 -M 'BEGIN {printf("%.60g\n",'"${in-0}"')}' < /dev/null
}

And use:

$ c 22* 33 /7                   # spaces or not, it doesn't matter.
103.714285714285714285714285714285714285714285714285714285714

Reading this pages comments, I see a UNIX/Linux program called calc that does exactly what you want. If on Debian / Ubuntu / derivatives:

sudo apt-get install apcalc

then you can:

calc 236-192

and if you add an alias alias c='calc' to your .bashrc or /etc/bash.bashrc then it just becomes:

c 1+1

on the command line.