how to add floating number in shell?

a=-1.4
b=42273.85
awk "BEGIN {print ($a + $b)}"

42272.4

I am expecting result as 42272.45, what is wrong here?

>Solution :

You didn’t specify a precision so awk picked one for you (%.6g, the default for CONVFMT, see https://www.gnu.org/software/gawk/manual/gawk.html#Built_002din-Variables):

a=-1.4
b=42273.85
awk -v a="$a" -v b="$b" 'BEGIN {printf "%.2f\n", (a + b)}'
42272.45

I’m also correcting your use of shell variables in an awk script above, see How do I use shell variables in an awk script?.