BASH as a simple calculator

As long as you are satisfied with integer results:

[darkknight@darkworld ~]$ echo $[32 * 98]
3136
[darkknight@darkworld ~]$ echo $[332 / 98]
3
[darkknight@darkworld ~]$ echo $[29 + 56]
85
[darkknight@darkworld ~]$ echo $[29 - 156]
-127