bc - how to do math from the command line
echo ‘25+7′ | bc - addition
echo ‘25-7′ | bc - subtraction
echo ‘25*7′ | bc - multiplication
scale - the scale variable tells how many decimal places to take your answer. The default is 0, unless using -l, in which case the default is 20.
echo ’scale=5;25/7′ | bc division
3.57142
echo ’scale=10;sqrt(7)’ | bc square root
2.6457513110
bc -q interactive mode