You can use calc:
If you just enter calc with no other arguments it enters an interactive mode where you can just keep doing math. You exit this by typing exit:
C-style arbitrary precision calculator (version 2.12.3.3)
Calc is open software. For license details type: help copyright
[Type "exit" to exit, or "help" for help.]
; 2+4
6
; 3+5
8
; 3.4+5
8.4
; 2^4
16
; exit
Or you use it with the expression as an argument and it will provide the answer and then exit
$calc 2 + 4
6
$
calc is similar to bc, I just like the way it behave as default better
