bc: set number of digits after decimal point

Question

bc handles numbers as integers:

# echo "100/3" | bc
33

bc -l handles numbers as floating point objects:

# echo "100/3" | bc -l
33.33333333333333333333

Is there a way to limit the number of digits after the decimal point?

Answer 1

Set the scale special variable:

$ echo "scale=2; 100/3" | bc
33.33

Answer 2

scale works only for division; if some geeks need it in multiplication, then you can do achieve this by using string manipulation. Say if you need to multiply 32 * 0.60 , answer is 19.20. If you need to get it 19 alone in answer you can get it by different methods.

1. Using String Manipulation

   $ S=$(echo "32*.60" | bc ) ; echo ${S%.*}
   19
   

   String Manipulation syntax: ${Variable%pattern}, this will delete short matching pattern that comes after %. For more String manipulation details see the Advanced Bash-Scripting Guide.

2. Using Scale as stated by **chronitis**

   $ echo "scale=0; 32*60/100" | bc
   19
   

3. To get rid of the trailing 0s, instead of string manipulation, one can also do a divide by 1.

   $ echo "0.232 * 1000" | bc
   232.000
   
   $ echo "0.232 * 1000 / 1" | bc
   232
   

Answer 3

you can also use printf command to round off result upto 3 decimals

# printf "%.3f\n" $(echo "100/3" | bc -l)
3.333

Answer 4

In addition to previous answers

echo "scale=2; 1.0150876" | bc

Returns

1.0150876

Add Math operations to get only 2 decimal numbers - (NUMBER*100)/100

echo "scale=2; (1.0150876 * 100) / 100" | bc

Now returns

1.01

Answer 5

Round-off

scale=2 truncates the answer to two decimal digits, but we can achieve round-off like so:

$ echo "a=12/104; scale=2; (a+0.005)/1" | bc -l
.12