bc is a command line calculator under linux.
parameter
-i force interactive mode
-l use bc's built-in library
-q Enter bc interactive mode and no longer output redundant information such as version
special variable
scale reserved decimal places, default 0
obase output base, default decimal
ibase input base, default decimal
case
interactive mode
$ bc -i -l -q
a=36
sqrt(a)
6.00000000000000000000
scale=2
sqrt(a)
6.00
obase=8
sqrt(64)
10.000
quit
non-interactive mode
$ echo "scale=3;9+8-7*6/5^2" | bc
15.320