bc: set number of digits after decimal point

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?

Asked By: Adam Matan

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Set the scale special variable:

$ echo "scale=2; 100/3" | bc
33.33
Answered By: chronitis

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
    
Answered By: SAGAR Nair

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
Answered By: Michal Zmuda

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
Answered By: spanky

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

# printf "%.3fn" $(echo "100/3" | bc -l)
3.333
Answered By: Rohit Khune
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